Looking for a good "small" game

Since you like the genre, Hack, Slash, Loot

Not sure if this can be considered high replay-ability but I did play it through 3 or 4 times myself and I thoroughly enjoyed it.

Bastion!

Escape Goat

Rogue Legacy, trust me!!!!

FTL is really awesome game and you can pause or quit in any moment.

Try FTL: Faster Than Light.
EDIT: Oh, ninja'd. :D

Sword of the Stars: The Pit.

Bloons Tower Defense 5 on Android and iOS. Endless replayabillity, seriously. :D

Thomas Was Alone

I like Legend of Dungeon too.

Spelunky.

Guacamelee is quite short.

Not really for the replayability but for the ability of being able to stop playing without too much hustle:
BIT.TRIP: Runner 2,
Joe Danger 2: The Movie,
Mark of the Ninja, and
The Swapper.

140 is a minimalist platform game, could last rather long depending on your skills, it has a high replayability because of its difficulty only.

Hotline Miami comes to mind

Desktop Dungeons, Nuclear Throne

• Plants vs Zombies - tower defense against zombies using plants
• Virtual City - very simple goods transport management
• Bus Driver - for relaxing if you know how to drive xD
• Space Pirates and Zombies - top-down 2D customizable squad spaceship shooter, one of my fav games :}
• Audiosurf and Beat Hazard Ultra - music-based games, highly replayable as long as you have music :P
• Bob Came in Pieces - a little side-scroller puzzle game where you're a customizable ship looking for your parts
• Home - a creepy side-scroller adventure that you can re-play in diferent ways
• World of Goo - side-scroller puzzle with goo-y physics

SteamWorld Dig : Fist Full of Dirt, is quite good, and not particularly long. Yet, it's something I'd play again. Lot of fun.

I'm not sure why it needs to be a short playthrough, if the goal is to waste time?

In any case, the ultimate in replayability goes by the name of Dwarf Fortress.

FTL has already been mentioned, so I'll also recommend an excellent time-wasting puzzle game: SpaceChem.

Hmm, roguelikes are small, and usually you die and die and die as you learn how to play so each playthrough tends to be short at the beginning. A bit painful for people who aren't into the whole ASCII thing, however... :)

But there's a fair amount of kinda-feels-like-a-roguelike you might consider like FTL, The Pit, Rogue Legacy, Spelunky, Teleglitch, etc. Have fun! :)

As for rogue-likes Eldritch is pretty cool, even though I suck badly at it :D Don't get put off by the blocky Minecraft-esque graphics, it's a pretty cool first person stealth rogue-like with a creepy atmosphere.

And maybe something else: Puzzle Quest 2! No idea if this is your type of game and while it isn't necessarily a short game, I would call it a "small" game :)

Gunpoint.

Dwarf Fortress, for sure. I recommend Masterwork:DF It has everything you could ever need, including multiple graphic packs to choose from.

If that one is too hard for you to get into, get Gnomoria! It is identical gameplay-wise, just not as deep or complex. I've been playing that lately and have been enjoying it quite a lot. I still prefer Dwarf Fortress in most ways, but Gnomoria is still a lot of fun, and one big bonus is that it has an actual usable interface. =P

If you really don't like games like those, maybe these may interest you:

• Worms: Armageddon
• Terraria
• FTL: Faster Than Light
• Gratuitous Space Battles
• Space Pirates and Zombies
• Hack, Slash, Loot
• Sword of the Stars: The Pit
• Unepic
• DEFCON
• Frozen Synapse
• Defender's Quest: Valley of the Forgotten
• Teleglitch: Die More Edition
• Braid
• Talisman: Prologue
• DoomRL
• Mysterious Castle (There are version for PC and Mac, as well as for iPhone/iPad)

DayZ

FTL