Pandemic Legacy is a co-op board game that raises the stakes by adding permanent (actually permanent) changes to the board as you play, and it’s amazing. Both season 1 and season 2 also happen to be on sale for $41 today, within $5 or $6 of all-time low prices.
Note: The different colors of each season are just that, color schemes. While there’s no functional difference between the editions, this allows you to keep two games going at once without getting confused.