While vacationing at the Jowai Resort on the planet Pokitaru, Ratchet and Clank come across a little girl named Luna who is writing a report for school on heroes. She requests that the duo do some heroic actions for her to photograph. Shortly after, Luna is kidnapped by robots. Clank then finds an artifact from an ancient race know as the Technomites. While Ratchet and Clank are on their way to rescue Luna, they encounter Captain Qwark, who is trying to find his true parents. Ratchet allows him to use the computer on their ship so that he won't follow them. Little do they know that Luna is actually a villain.
On the planet Kalidon, Ratchet is then kidnapped by Luna, and Clank is left at a junkyard. While at the junkyard, Clank grows bigger and sets off to rescue Ratchet. At the same time, Ratchet's DNA is taken and used to produce massive armies of clones. Otto Destruct, emperor of the Technomites, realizes Ratchet's potential and attempts to make the ultimate Super-Soldier. After being defeated, Luna tells the cloning plot to Clank and how the Technomites are angry for not being given credit for their technological advances.
Clank tries to get the coordinates to the clone-maker, but Luna is infected by a computer virus which allows the Technomites inside Luna to then enter Clank. Ratchet shrinks himself and enters Clank to clean his robot buddy out and get the coordinates. Ratchet defeats the Technomites. On Quodrona, Ratchet disposes of several clones. Otto reveals that what Luna told them was merely a story, and that the real plan is to steal the knowledge of every single being in the universe for himself. Captain Quark, who was persuaded into thinking that Otto is his father, temporarily fights with him. After beating Otto and switching his brain with that of a space-monkey, Ratchet and Clank learn that Quark's parents were killed by defective equipment. Ratchet returns to Pokitaru hoping he can still make his scheduled massage time.
Like previous entries in the Ratchet & Clank franchise, gameplay is a mix of platforming and shooting, with Ratchet and Clank traveling to various planets, exploring the local land, purchasing new weapons, and finding coordinates to other planets. There are also the occasional miscellaneous elements like space combat, mini-games, rail-grinding, and vehicular battles. In one portion, players will control Clank and his small army of robots, and the player can unlock some bonuses if they have a save game from Secret Agent Clank. Players can upgrade weapons and health over time, and instead of purchasing armor, pieces can be found within levels or as prizes for mini-games. Combining these suit pieces will offer different looks and damage-reduction rates for Ratchet. There are also 25 skill points to figure out, each unlocking specific in-game cheats, like Big Head mode, as well as various skins for Ratchet.
Ratchet will visit 10 different locations, with an eleventh unlockable "planet" called California, where players can explore the HIG Treehouse. HIG stands for Huge Impact Games, the developer of Size Matters. Here, Ratchet can test out a weapon cut from the game, see unused Ratchet clones, take on a grinding section missing from the game, and see a test module's full animations, as well as explore the building freely.
|Pokitaru||Jowai Resort||A small, tropical island planet, one of the most popular getaways in the galaxy. First appeared in the original Ratchet & Clank. An Infobot previously mentions that the planet has constant sunshine 24 hours a day. Ratchet and Clank are vacationing here after the events of Deadlocked, relaxing just a bit before starting a new adventure in Size Matters.|
|Ryllus||Vetega Jungle||Mostly inhabitable as the planet is covered entirely in plants. The planet's fauna and flora are extremely hostile to visitors. This planet was colonized by the Pygmy Tribesman and Technomites long ago, and it is here that they built a temple, which housed a hidden holographic map of other planets they had colonized. Ryllus is the only planet in the franchise, other than Torren IV in Polaris from Ratchet & Clank Future: A Crack in Time, to feature a natural ring system.|
|Kalidon||Mechanoid Factory||This planet has long been occupied by the Technomites due to the barren and inhospitable nature of the landscape. It is also the source of robot control units (RCUs), built in excess at the Mechanoid Factory. Skyboarders often used emptier parts of the planet to practice racing. The planet highly resembles Batalia from the original Ratchet & Clank.|
|Metalis||Junkyard LXIV||A junkyard planet found in the Solana Galaxy. Old, out-of-date automatons are discarded here, and they have together created the Destructive Derby, pitting robotic vehicles against one another for sport and prizes.|
|Dreamtime||N/A||A nightmarish realm located within Ratchet's subconscious. While having his DNA extracted by Technomite scientists at Medical Outpost Omega, Ratchet "visits" this location, searching for a way out. Players must battle against previous memories and villains from former games, and cameos are aplenty with Darla Gratch, Chairman Drek, and the Plumber popping up in the background.|
|Medical Outpost Omega||Surgical Facility||Medical Station XL6, which is more commonly known as the Medical Outpost Omega, is a space station operated by the Technomites for various medical research projects, such as cloning an army of Ratchet super-soldiers.|
|Challax||Technomite City||Challax is a rocky, desert planet. Surrounded by two suns, the climate is extremely hot, making for one inhospitable landscape. Only the Technomites--as well as some insects--have been known to live on this planet.|
|Dayni Moon||Farming Cooperative||Dayni Moon, home to various crops and the galaxy-famous, one-legged Weresheep, is best known for its agricultural facilities. Due to the planet's rotation speed, day to night changes in a matter of minutes. This is the only planet in the Ratchet & Clank series to have a day/night cycle.|
|Inside Clank||N/A||This is a special level, not a planet, which involves Ratchet using the Shrink Ray to turn himself teeny tiny and enter a defunct Clank's body to clear out any Technomites within and find out the coordinates to their cloning factory.|
|Quodrona||Clone Factory||Quodrona is a volcanic planet, where Otto Destruct keeps a base of operations underground. A destroyed city can be seen in the background. It is or was at some point inhabited solely by the Technomites.|
|California||HIG Treehouse||A secret level accessible in Size Matters by either collecting all of the skill points and accessing it through the cheats menu or messing around with your PS2's clock system to get you through a specific set of doors on Metalis at a specific time period. The HIG Treehouse contains items that did not make it into the final game, such as characters and weapons, concept art, Easter Eggs, and secret codes.|
There are fourteen armor sets for Ratchet, with some only available via New Game+, and one unlockable metal skin for Clank.
Old School Suit
The Old School Suit is the first "suit" Ratchet wears in the originally Ratchet & Clank, consisting of just a pair of pants and gloves, appearing to offer no protection whatsoever. In Size Matters, Ratchet begins the game wearing this "suit," and continues to wear it during cutscenes no matter what armor set he is currently wearing during gameplay.
This set of armor protects Ratchet by coating him in super-heated, carbon-coated ceramic tiles. Due to extremely high operating temperatures, the armor instantly sets fire to anything it touches. While wearing this full set, the Omniwrench 10K becomes super-heated, setting enemies on fire with every hit. Enemies on fire take burn damage over time, eventually succumbing to the flames. Damage reduction is 28% when wearing the full armor set.
Sludge Mk. 9 Armor
With the full set on Ratchet, every swing of his Omniwrench 10K spreads acid on the ground, hurting any enemies that crosses over it. Damage reduction is 42% when wearing the full armor set.
With all of the pieces of the Crystallix armor on, Ratchet can create crystals on the ground after performing a hyper-strike. These crystals can then further damage enemies. Crystals can also be formed from every third strike in a multi-hit combo. Damage reduction is 56% when wearing the full armor set.
Based on earlier prototypes of Gadgetron's Electric Reactive Armor, the Electroshock armor utilizes a high-power capacitor to energize two plates composing the armor's surface. A full set of Electroshock armor has such a high charge that electricity arcs across its surface and then along Ratchet's wrench. Jumping and then attacking the ground with Ratchet's wrench causes a wave of electricity to form around him in a large radius, damaging all nearby enemies. Damage reduction from wearing the full armor set is 74%.
While Ratchet wears the full set of Mega-Bomb armor, damage from enemy attacks is built up and stored as its own energy, which is indicated by a red glow. With this stored energy, Ratchet can then attack with his wrench, dealing a large amount of damage at once. However, the charge wears off after a short while if the energy is not released. Damage reduction is 84% from wearing the full armor set.
Using technology from an ancient race only recently uncovered by Gadgetron anthropologists, the armor set contains super-chilled pockets of dihydrogen monoxide packed between tritanium wafers to create a composite armor unlike anything seen before. It is the most damage-absorbent armor in the first playthrough of Size Matters, as well as the known universe, with damage reduction at 92%. A hyper-strike creates an ice shield around Ratchet. Hitting enemies with the wrench freezes them solid though the ice will melt away after a short time.
The Fire-Bomb armor is created by mixing parts of the Mega-Bomb and Wildfire armor sets. The Omniwrench 10K becomes heated to the point that it ignites the air by forcing pocket energy through the pair of Wildfire gloves. On the third swing of a wrench-hit combo, a fireball is generated, exploding against any target in its path. Also, tossing fireballs and defeating enemies with it counts towards leveling up the Scorcher, even if it is not equipped. Damage reduction is 84% when wearing the full set of armor.
Shock Crystal Armor
The Shock Crystal Armor contains energized Crystallix armor pieces fused with charges from the Electroshock armor, which cause a sudden increase in the growth of quasicrystal formations. Performing a hyper-strike creates a persisten quasicrystal formation that both electrocutes enemies and neutralizes any enemy projectiles. Unfortunately, these formations are very fragile and can be easily shattered.
Combining technology from the Wildfire and Sludge Mk. 9 armor sets, the Wildburst set packs minute Wildfire ceramic wafers inside a superheated bubble of viscous Sludge goo, acting as a thickener. When Ratchet performs a hyper-strike, a sludge bubble forms that explosively expands, releasing burning sludge in a small radius and damaging enemies. Damage reduction is fairly low at 36% when wearing the full armor set.
Ice II Armor
This armor is created by combining parts from the Hyperborean and Crystallix armor sets. With the full armor on, Ratchet is capable of forming rhombohedral crystalline in huge numbers to produce an ice wall by executing a hyper-strike. This ice wall protects against projectiles, but will shatter after a short period of time. Damage reduction rivals the full Hyperborean set at 92%.
By combining pieces of the Chameleon, Wildfire, and Sludge armor set, the Stalker armor focuses all of its camouflage capabilities into the Ratchet's wrench, effectively making it ethereal. Although the wrench initially passes through enemies and deals no damage, at the same time it also injects a large dose of Wildfire and Sludge solution directly into the enemy, both poisoning and setting them on fire. Ratchet is nearly invulnerable with the full armor set on and damage reduction at 96%.
Using fully-realized active thermoptic camouflage on top of a depleted-thorium core, this armor set not only provides personal protection equal to that of some light tanks, but also renders Ratchet nearly invisible while moving. It makes Ratchet harder to target by creating holographic "clones" which are left behind, distracting enemies. The holograms fade away after a short period of time, and the full armor set provides damage reduction of 96%, putting it on par with the full Stalker armor.
Triple Wave Armor
With the full armor set, the feedback loop is destroyed when Ratchet performs a hyper-strike. Capacitor energy is then released into a damaging wave that exhibits electric, fire, and sludge properties all at once. Damage reduction with the full armor set on is 64%.
Ratchet can participate in Skyboard races for bolts and special prizes on the planet Kalidon and the remains of Medical Outpost Omega. These races are similar to the previous Hoverbike races in Going Commando and Deadlocked and Hoverboard races in Ratchet & Clank. To win, you have to place first after a set number of laps.
The Skyboarder initially challenges Ratchet to race on Kalidon, offering the Shrink Ray and Polarizer as prizes. However, it is known that the Skyboarder is always willing to cheat to win, and he is believed to be a tribute to Hunter the Cheetah from Spyro: Year of the Dragon.
There are four types of Clank challenges in Size Matters: Destruction Derby, Gadgebot Toss, Gadgebot Survival, and Clank in Space.
In Destructive Derby, the objective is plain and simple: destroy all opponents. You take control of a different vehicle based on the challenge selected, and your goal is to damage opponents' vehicles to the point where they no longer operate. You can use items picked up in the arena, such as seeking missiles or droppable mines, or use whatever power your vehicle has, such as ramming or turning on attached buzzsaws, to dish out damage. You can also use traps within the arena, like bumper blocks, to your advantage.
In the basketball-inspired Gadgebot Toss, players control a robot that is able to pick up a smaller robot and toss it around. The goal is to get it through a green field somewhere in the arena. Opponents can try to knock it out of your hands or throw bombs at you, causing you to drop the robot. You can use the same tactics against them when they have a robot ready to throw, too. Reach the decided amount of points, and you win.
For Gadgebot Survival, you must help a bunch of unstoppable walking robots reach an end goal Lemmings-style. The levels themselves are a puzzle, and you can have each robot perform four different actions: swing, electrify, detonate, or bridge. To win, you must get a specific number of robots into their home base.
Lastly, Clank in Space consists of a giant Clank soaring through space, shooting down countless enemy spaceships. After a set number of enemies are killed, Clank will be able to store a rocket in his arsenal, which should be saved for large swarms of ships or boss fights.
Ratchet & Clank: Size Matters includes a few multiplayer modes, such as Capture the Flag, Deathmatch, and Iron Lombax. For the PSP, you could play online with up to four players, but only two players via the cooperative player mode for the PS2 port. As of June 27, 2012, online services for multiplayer have been shut down.
The original PlayStation Portable version of the game received overall positive reviews. Game Informer rated it 9/10 and awarded it the "Handheld of the Month" for April 2007. IGN gave it 9.0/10. On the other hand, the PlayStation 2 port of the game received lukewarm scores, with IGN giving it a score of 6/10, citing its poor graphics, dull gameplay, and many glitches.