While it lacks some of what made Left 4 Dead so revolutionary, Payday: The Heist is a must buy for anyone who's a huge fan of Left 4 Dead. Personally I'd recommend the four pack, so you don't have to rely on random nitwits, but that's a matter of personal preference. Still, for the price of many games of similar quality, you can acquire three giftable copies, what's not to love?

Character progression and varied circumstances in the missions make this game quite replayable. The only real down side here is the AI is somewhat less than stellar, sometimes stepping in front of automatic weapons fire, falling behind, etc.

Terraria is a really fun little game, for the price you can't beat it. They update the game regularly with new items, mechanics, and NPCs. It is one of the few games I can honestly say has infinite replayability.

An interesting take on the MOBA genre, with per-character persistant leveling, as well as per-match builds. There is a 3 player PVE map where you go around farming and fighting 3 AI immortals, until you can break open crystal prisons and free your own AI giants to help fight the giants defending the enemy side of the map. When you destroy the enemy shrine, you free a huge dragon, and can shatter the final crystal prison to free an ally to help you take down this end-game boss.

The rewards for PVE and PVP are fairly substantial, with fewer than 50 PVE games giving enough prestige to unlock an immortal. This, as opposed to League of Legends, where it would take about 50 hours of constantly playing (and winning) matches to get 6300 IP, to unlock most of their champions. At the moment the character roster isn't huge, but I expect that it will grow, and perhaps Petroglyph won't take years to come out with additional maps with new gameplay mechanics. This seems like a game to watch.