I really wish they'd add one to the game.
Solo or group play (group of course harder)
Each round gates open and the enemy comes out. Each level getting harder but with a larger reward. Highest level achieved makes it to leaderboards.
After every x amount of rounds get special tokens or keys for goods. I dunno just something that popped in my head I'd like to see.
...there are several.I'd love a colosseum