A free Portal
-themed prototype level is now available in Killing Floor
, Tripwire Interactive's co-op survival/horror first-person shooter. The game itself is also currently on sale
at a 50% discount. Likewise, a new Portal -themed level is available in The Ball
, Tripwire's first-person action/adventure game, which is also on sale
for half off. This video
shows off the new level in The Ball. Both games are also part of The Potato Sack
, Valve's 13-game indie bundle, which is currently 75% off.