I thought it wouldn’t work and kept the old mouse on standby on my desk for gaming but after a little while it was left gathering dust. It works surprisingly well and finally trained me to use the thumb buttons as the MX Vertical lacks a rocking wheel for back/forward.
Spelunky, for co-op. I definitely prefer the first game for solo but it only has local co-op. Spelunky 2 has both local and network play but the difference between having a single camera follow the one flag carrier and everybody having their own screens is like playing a different game. Single screen is total mayhem.