If you like free things, especially free games then check out Desktop Dungeons. I heard about this from the web show Extra Credits. I had a look for myself and it's actually pretty interesting. You should watch that video in case you're interested in other games you might not have heard of. The game is a roguelike, which I had no idea even existed until I downloaded the game. I guess people are pretty into the dungeon realm of things, but I find this game quite engaging because of its depth of choice. Unlike other rpg's this game revolves around exploration. Exploring allows the player to discover more power-ups, gold, and the occasional baddie for power-leveling. It also gives the player vital health and mana (for magic spells) points. This creates a unique scenario where in you must decide whether pushing forward for another power-up is more important than future hitpoints for exploration. Anyways, it's a fun game and each session typically lasts for about 10-20 mintues. Oh, and the game will kick you ass.
Yeah man, thanks for posting this. It's a fun little time-waster. Doesn't take a lot of skill, just a little strategic planning.