Prop Hunt sounds like it would be a fun event

A base defence mode could be fun. Earn credits each wave for kills, extra for mining resources at each level, spend them on turrets and such for the base. Could be a base that drills down and mines as it goes, each time it drops into a deeper cave system, a new wave begins and you have to defend it while it drills, or perhaps have to repair it in various places to move on whilst also defending it.

Of course, what it REALLY needs is a battle royale mode, obvs /s

While I love that every mission ends in a drop pod escape sequence, it would be interesting to have one mission that was different.

Maybe a survival/horde mode where you just have to last as long as possible or complete as many small tasks as possible before you inevitably wipe. That obviously doesn't fit into the success/failure model of the rest of the game so maybe it would have to be a seasonal event or something.

PvP.

Two teams of 4 dwarves, starting at opposite ends of the cave, one from "another rival company, damn traitors" (which team? Who knows). Can't leave until the other team is all downed. Whoever lives gets a bonus, but the losing team still gets credit for completing the mission if they complete a secondary objective. Crank up the bug spawns to the point where both teams might consider taking a break from fighting to team up during a wave.

Maybe it wouldn't work, and maybe it would foster a negative environment, but damn a dwarf can dream.