Orcs Must Die is a game that, in the later levels, can result in the player leaving the game to run for hours. Unfortunately this doesn't work for Stadia, because the player will be kicked out of their session to save bandwidth on the Stadia server. Being kicked results in the game session ending, erasing all unsaved progress.
Besides all of that, the game is currently very lacking in traps and trinkets, almost to a "Early Access" degree.
Skip the Stadia version and wait for PC and console release.