WARNING: Desktop Dungons, the shockingly addictive Rogue-like with persistent city and hero building elements, has left browsers and arrived on Steam. You'll be able to play it at home on Valve's client, then on your browser at work, feverishly alt-tabbing at every footstep, the sweat running down your brow and soaking your fashionable tie.
Your every waking moment will be consumed with playing this game or thinking about it, at least when you're not on the move since it requires Flash. Be sure to this valuable time to call your loved ones, since you'll see precious little of them if you install Desktop Dungeons.
Or, like, play it in moderation. Here's a preview from years back.