Oh, this is my specialty. I travel a lot and I always try to have a few games on my MBPr (late 2013 8 GB) to kill time that aren't graphically demanding, aren't affected by MBP/OS X's shortcomings and can even be played without a mouse (although I always carry one and sometimes even a gamepad)

Here are some suggestions, I can specify more if you say what kind of games you like:

Roguelikes

• The Binding of Isaac: Rebirth
• Crypt of the Necromancer
• Dungeons of Dredmor
• FTL
• Neo Scavenger
• Nuclear Throne (it needs a mouse)
• Risk of Rain
• Tales of Maj'Eyal: one of the best traditional roguelikes imho, I have it on Steam, but it's free on its website. Really tough.

RPG

• LISA: it's like a darker, crazier, side scrolling Earthbound.
• The Banner Saga: SRPG, it runs very hot so I wouldn't play it on battery
• Shadowrun Returns/Dragonfall: same as TBS.

Platformers (best played on a gamepad for the most part)

• Braid
• Cave Story+: the first indie hit and still one of the best metroidvanias ever.
• Escape Goat 1 & 2: great puzzle platformers to play in short bursts.
• FEZ: another charming puzzle platformer. I'm think it's a bit overrated, but it's very good any way.
• Guacamelee: more metroidvania, but I'd wait for the Super Turbo Championship Edition to be released for OS X.
• Mark of the Ninja: probably my favourite stealth game ever.
• Offspring Fling: puzzle.
• Stealth Bastard Deluxe: another good, although simpler, stealth platformer.
• SteamWorld Dig: Short but fun, sort of a mixture between a metroidvania and Spelunker with all the digging.
• The Swapper: more puzzle platforming about swapping places.
• Thomas Was Alone: super short, super simple, super fun puzzle platformer.
• Toki Tori 1 & 2+: even more puzzles.

There's an incredible amount of amazing platformers on Steam, but I wouldn't recommend playing them without gamepad on a laggy OS and a laggy screen: Broforce, Dust: An Elysian Tail, Dustforce, Electronic Super Joy, Savant: Ascent, Shovel Knight, Super Meat Boy, Unepic, Valdis Story...

Others

• Antichamber: short and super wacky first person puzzle game.
• Bastion / Transistor
• Gunpoint (needs mouse)
• Hotline Miami (needs a mouse, the first one is much better)
• Prison Architect: I'm not a big fan of city building games, but I enjoy building and managing a prison from time to time.
• Don't Starve: also not a big fan of survival games, but I've sunk quite a few hours on this one.
• Kingdom Rush. the third and last genre I don't enjoy much: tower defence games. This one is casual and great.
• Dungeon of the Endless: same as above, but this one is more roguelikey.
• HuniePop: there, I said it. I would never play it in public though.
• Race the Sun: it's about flying fast while avoiding obstacles.