Do you like loot? Then Space Siege might be for you. If you have an insatiable lust for items with higher stats than...
Wait, no, that was Too Human.
But the game is more simplistic than that. Enemies don't drop specific loot-style items. Instead, they all bleed a generic form of currency called upgrade parts that you can cash in at a workbench (basically a vendor station) located next to each save point. This is where you access basic common character upgrades like health, crit chance, armor rate, attack speed, and so on. You don't earn experience points and gain levels like in a traditional RPG, so this is the only way to advance your character's basic attributes.
In lieu of ubiquitous, scrumptious loot, there are only 10 fixed weapons that are parceled out to you at set points in the storyline, and you can use upgrade points to further improve the stats on these. Strangely, the weapons don't always become more powerful in the order you acquire them. More than once I picked up a new weapon to find it actually had worse stats than the one I was already using, even after upgrades, so I just stuck with the old one. But these games are all about finding shiny new toys and laying waste with them, so only getting to use about half the weapons for any real length of time was unsatisfying.
There's also a skill tree with only two paths--combat and engineering--and you're free to pick and choose skills between the two as you go. Again, you only get a specific number of skill points at predetermined places in the story, so you can't really dabble in both trees if you want to specialize in the better skills at the end of either of them.
With no classes, such limited customization options, and the total absence of delicious loots, the character-building in Space Siege ended up feeling shallower than I would have liked. The game also got way too easy by the end. Since I'd maxed out my dude and weapons with my surplus of points, and gained a number of overly powerful abilities, I dominated the last few bosses and breezed through to the ending unopposed.
The game's premise isn't bad. A couple of centuries hence, humanity's spacefaring has stepped on the toes of a crab-like alien race called the Kerak. Taking great offense, they've come to eradicate our species and destroy Earth. You're a soldier on the lone colony ship to escape the Kerak's brutal invasion, but you wake up from a few weeks in cryosleep to find that a single enemy pod has breached your ship's hull and flooded its interior with aliens. Now you need to kill them all, and deal with any other "surprise" opponents thrown your way over the course of the game as well. (Hint: the appearance of those other opponents isn't a huge surprise.)
The story moves along at a brisk enough pace, but it also uses some similar plot devices as--and in a couple of cases, blatantly lifts identical plot points from--games like F.E.A.R., System Shock 2, and Doom 3, which ultimately made me feel like I'd seen most of this before. The endgame is also disjointedly paced and leads to a rather abrupt, unsatisfying climax.
Coincidentally, Space Siege does share one aspect with Too Human: the ability to make use of performance-enhancing cybernetic upgrades that come with a vague warning about the questionable wisdom of sacrificing one's humanity to become a raging badass. These warnings don't translate into alternate gameplay incentives, though. The cyborg replacements for your arm, legs, chest, spine, eye and even brain all come with significant combat bonuses that are hard to resist, and the game doesn't really give you a reason to resist them, other than exactly two skills on the tree that require you to be almost fully human. (Compare those meager two to at least a dozen useful skills that demand you do take the upgrades.) There are three endings in the game based mostly on whether or not you want to install all the cyborg gear, but they're all equally short and lousy and in no way justify missing out on those buffs and skills. I ended up using every cyborg upgrade without blinking.
There are a couple of neat aspects worth mentioning. Early on you pick up a capable combat robot called HR-V (read: Harvey) that you can control almost as extensively as you can your own character. HR-V gets its own skills and commands, so you're practically controlling two characters at the same time, and the scrappy little bot can get you out of a tight spot occasionally. He's just as good at getting himself killed, though. Also, somebody left tons of explosive barrels and canisters lying all around your ship, and the game has a nice physics model that sends objects flying every which way when you cause a lot of explosions with these. I stopped a few times just to blow up a room full of boxes even after all the enemies were dead.
Space Siege is genuinely fun for a while, but at some point in the dozen-or-so-hour campaign it became more tedious than entertaining, and I just wished there was more depth in the mechanics to hold my interest. A couple of glaring omissions didn't help matters, such as cooperative play integrated into the campaign (it's instead relegated to a series of unrelated one-off missions, launched from a really clumsy external application, that don't really go anywhere) and the ability to remap your controls at all, which, just...well, that speaks for itself. With quality dungeon crawlers like Titan Quest now going for bargain-bin prices, and Diablo III threatening to redefine this specific genre in the relatively near future, Space Siege is hard to recommend at its full asking price, but it's entertaining enough for hardcore fans of this kind of game, if you can find it at a reasonable discount.