Borderlands 2 screenshot of a snowy area

If you absolutely hate free time, and you don't mind your backlog getting even bigger, you might want to check out the most recent Humble Bundle as its filled with highly enjoyable and rather lengthy games. If you prefer singleplayer games you have the absolutely massive Endless Legend 4X strategy and Van Helsing ARPG to explore, while those of you more inclined towards co-op have the entirety of the Borderlands series to shoot, loot and explode your way through.

Before you dive in, however, it is worth repeating that completing pretty much any of these games will require a considerable time investment. So if you're only playing casually, don't feel the need to grab all of them as you're most likely never going to reach the end of each one. With that little bit of warning now out of the way, here's the full list of games and the tier they appear in:

Pay what you want:

Borderlands: Game of the Year Edition

The Incredible Adventures of Van Helsing: Final Cut

Wurm Unlimited

Pay more than the average of $4.97 (about €4.22) to also unlock:  

Endless Legend: Classic Edition

Borderlands 2 and all DLCs

Guild of Dungeoneering

Pay $10 (about €8.48) or more to also unlock:    

Borderlands: The Pre-Sequel

I've never played Wurm Unlimited or Guild of Dungeonneering so I won't comment about their quality, but what I will say is that the second tier is well worth a purchase for Borderlands 2 alone. Its one of the most enjoyable co-op shooters I've played in a very long time, and while half of its DLC is mediocre the other half is so good it easily eclipses the weaker ones. So if you're only going to play one game out of this whole bunch, make sure its Borderlands 2 alongside a couple of like-minded friends. Have fun!