https://www.gamespot.com/articles/new-humble-bundle-to-play-with-friends-or-enemies/1100-6459000/

Humble is at it once again, with a money-saving proposition on a bundle of PC games for Steam. As always with Humble Bundles, you can spend any amount you choose, starting with $1 to get the initial tier of games. Scoring games in the higher tiers costs more money, but it's always much less than if you bought them separately. This time the focus is on multiplayer games. So choose a tier, gather up your friends, and start playing. This Humble Bundle deal ends May 28.

Paying just $1 gets you the stick figure fighting game Stick Fight: The Game, the co-op beat-'em-up Rampage Knights, and the multiplayer puzzle game Tumblestone. Crank your payment up to above the average amount, and you'll get access to those games, plus the second tier. This set includes the competitive duck shooter Duck Game, the 3D parkour game Hover, and Besiege. Besiege is probably the most notable game in this tier, as it has you construct siege engines in order to destroy everything in your way, from quiet villages to battle-ready fortresses.