I just realised! Left 4 Dead 2 is on a free weekend, and right now it’s 75% off (£3.74 in the UK) which is a real bargain. If you don’t have it, now is a good time to get it! It rarely gets cheaper than this.
The second game improves on a lot of things from the first game, and by comparison has a very Borderlands 2 wub wub level of gun selection. The number of mele items has also increased. It is by no means a ‘proper’ sequel, but the way the first and second games are intertwined is pretty cool. The AI isn’t any better, but this is a game best played with friends, so grab a few friends, play co-op and kill some zombies!