I'm looking for some good platform games on the PS3 (for my girlfriend).
 
Criteria is as follows:   

• Side-scrollers are always good, but they seem to be somewhat rare.
• Combat-based platformers seem to enjoy moderate success with her.
• Preferably not on PSN, because of some connectivity and bandwidth issues.
• Content should not be too dark, e.g. sadly I don't think my girl would go for Alice: Madness Returns.

• LittleBigPlanet
• Ratchet & Clank: Tools of Destruction
• LEGO Batman: The Video Game

That's a narrow search margin, I don't know that a lot of what you look for exist outside of the PS1/PS2 era. But I have some suggestions:

• DeathSpank - It has a cozy girlfriend mode, or maybe she would like to be DeathSpank
• Rocket Knight seemed ok in the QL
• Trine
• Mirrors Edge
• Outland

• Ratchet & Clank: A Crack in Time
• Sly Cooper Collection
• Prince of Persia(2008)
• Prince of Persia: The Forgotten Sands
• Prince of Persia collection

I have all of these and they are great. Others I'd suggest would be Portal 2 though playing co-op could cause some fights.

Ratchet and Clank: A Crack in Time. It's one of my favorite games this gen and not too many people seem to know about it.

Sly Cooper Collection may be a great idea, but the only downside I see to it are some frustrating Murray missions which spike in cheap difficulty (along with other myriad of parts that can be 'cheap').  Also Littlebigplanet 2 is out now so if the first one was a hit then this should do fine.  Basically just beware of small instances of cheap deaths or weird difficulty spikes in some platformers. 

If you never played Gunstar Heroes on the Genesis before, nows the time you should. Its on PSN, its a side scroller, and its intense.

I've been enjoying the Sly Cooper HD Collection, lots of game for your dollar.

@Zacagawea said:

Ratchet and Clank: A Crack in Time. It's one of my favorite games this gen and not too many people seem to know about it.

Totally agree, amazing game. Also, El Shaddei is out soon, seems to be a good deal of platforming in that.

Outland is fantastic. Definitely get that one.

If you have a 360, then Ms. 'Splosion Man would be perfect for what your asking. But its a tough game, I guess..
 
Sly collection and Outland are other great options...

The Sly Collection. You get 3 games for $30, the platforming is easy and fun, the writing and characters are top notch and they still look good to this day. I got 100% in the first 2 and am currently playing through the 3rd. If you want bang for your buck get It.

As someone else said Prince of Persia 2008 is another great game. You can get it for $20, no death penalty, beautiful graphics, likable characters and fluid combat that is easy to learn but satisfying when you pull off a big combo. Please let us know what you decide to get.

• Content should not be too dark, e.g. sadly I don't think my girl would go for Alice: Madness Returns.

• Littlebigplanet 2
• Sly Collection
• Ratchet and Clank: Clock Blockers (I will never let that go)
• The only other great platformers I can think of are on PSN.
• Sonic Ultimate Genesis Collection is filled with some good co-op and platformers

Also sorry but a lot of the best platformers for the system are on PSN. They include

• Outland
• Limbo, next week
• Trine, great for co-op
• Braid

Forgot to say pick up a copy of Portal 2 and play through the co op mode with her. I played with a girl who had never really used two thumbs sticks in a video game and a few chapters in she had it down and loved it.

• Portal 2
• Uncharted Series
• Prince of Persia '08
• LBP2
• Sly Cooper Collection

Thanks for all the suggestions so far, guys. I know my criteria is very restrictive, but my lady isn't easily impressed. I'll definitely let you guys know what I ultimately decide on; I'm still compiling my list of possibilities.
 
@X19 said:

@BombKareshi said:

• Content should not be too dark, e.g. sadly I don't think my girl would go for Alice: Madness Returns.

She will love the art design. Even if she doesn't play it you should rent it at least as it's fantastic.

@BombKareshi: While I think Alice is fantastic, 5 hours in and having a blast, I can see that not being everyones game. You should defiantly check it out though when it goes on sale on Steam or at stores, got mine for $39 which isn't cheap but it's better than $59.

1. Ratchet and clank  future:a crack in time. 
Since you have Tools of destruction i highly recommend Ratchet and Clank:A crack in time. It's just as good if not better than tools of destruction. There are a few new weapons and there is more to do during the space sections as you travel from planet to planet, in addition to the space shootouts you can land on moons for simple platforming sections.You also get to play as clank in some very clever time bending puzzles. The game is great value as well, with about 10-15 hours of gameplay. 
 
2. Prince of persia)2008) 
This cel-shaded reboot of the prince of persia is a great game. It has great graphics, streamlined gameplay which is easy to learn and a decent story as well. the one on one combat is deceptively simple but really satisfying when you pull of 10-14 hit combos. 
 
3. Little big planet 2 
You have the first one and if you loved it you'll love the 2nd one as well. 
 
4. Consider renting movie tie-ins  
 Most of them are platformers and are usually very simple.They can be beaten in one day. and most of them also have couch co-op. Toy story 3 is a good option

1. Ratchet and Clank: A Crack in Time - definitely a blast to play, can't go wrong with this one.
2. The Sly Collection - 3 games for the price of one.  I've been playing through this and enjoying it quite a bit.

Little Big Planet 2 if you liked the first one, it's a nice improvement

I'm enjoying Outland at the moment so I'd recommend that.

You might want to check out PixelJunk Eden.  It's not a conventional platformer like R&C, but it does involve a lot of leaping from area to area while gathering stuff. 
 
Also, I'm not sure if it counts since I've never played it due to my fear of heights (some games can make me nauseous), but would Mirror's Edge be considered a platformer?  The videos I've seen suggest platforming elements.

Alice?

Littlebigplanet 2 is some of the best gaming fun i have had with my girlfriend.

If anyone is interested, here's my list of considerations thus far: BombKareshi's Girlfriend Watch List.
 
@mikey87144: @Masha2932: @MKSKILLZ16: @rawrsair: @Rowr: (everyone who recommended LBP2)
LittleBigPlanet 2 is definitely on the list, but since we're still working our way through the first one, I think I'll delay that one for now.
 
@mikey87144 said:

• Sonic Ultimate Genesis Collection is filled with some good co-op and platformers

4. Consider renting movie tie-ins 
Most of them are platformers and are usually very simple.They can be beaten in one day. and most of them also have couch co-op. Toy story 3 is a good option

You might want to check out PixelJunk Eden.  It's not a conventional platformer like R&C, but it does involve a lot of leaping from area to area while gathering stuff. 
 
Also, I'm not sure if it counts since I've never played it due to my fear of heights (some games can make me nauseous), but would Mirror's Edge be considered a platformer?  The videos I've seen suggest platforming elements.

I'd also recommend Braid (though it's PSN) 

I'd also recommend Braid (though it's PSN) 

It doesnt quite fit your criteria, though its close. Lara croft Guardians of light is some great coop platforming fun.

@BombKareshi said:

@ajamafalous: If you're talking about Alice: Madness Returns, I'm sure it's a great game, but as I mentioned in my opening post, I don't think she'll go for it.

Somehow I totally missed that part.

Anyway, gonna back up the people that said Ratchet. Great games, pretty forgiving.

Also beware of Pixeljunk eden it's possibly one of the most frustrating games I have ever played. I understand why some people like it  but it has a very strict time limit  and  strange controls.

All the obvious answers have been given, so I'll suggest something slightly different. How about Enslaved?
Mind you, the PS3 version isn't great with a lot of technical issues, so if you have a 360 you probably want to get it for that.
 
The Bionic Commando Rearmed games are pretty good too (I know you said no PSN, but it's hard to think of any sidescrollers on disc).

Ratchet and Clank: Quest For Booty, Ratchet and Clank a Crack in Time, The Simpsons Game, The Sly Cooper Collection, Alice: Madness Returns, Lego Games, Portal 2

Rayman:legends! Its my absolute favorite.

I'm a girl who isn't a huge "gamer" but I love side scrollers and classics like sonic and Mario type games.