The Room is awesome I agree, but also short. You'll definitely enjoy it while it lasts if you like puzzle games, though. Two more suggestions...
Rayman Jungle Run - I picked it up when it was on sale for a buck, but it's still an awesome game for $3. It's a running platformer, meaning all you control is jumping/flying/etc and the game controls direction (and speed, for the most part). Beautiful graphics, fun music, simple controls, and a sense of humor.
DragonVale - If you're the collecting type, this one will occupy you for months or longer. Like Simpsons Tapped Out, this is a long-term investment game unless you want to dump tons of cash. On the plus side, it also means you can pick it up for five minutes and then leave it for six hours, and it will reward you.
And then of course there's Minecraft.