My suggestion is going to be very unoriginal, being based off the popular FPS Call of Duty: Black Ops. We should have a minigame where you can only use guns and fight against constant hordes of enemies. As you chew through the waves, the enemies get stronger, and every now and then, add a mini boss to catch people off guard. Also, say every 10 waves, you can heal up, change gear at a safe house (got that idea from Left 4 Dead). And maybe have some powerups like in Blast Network and pickups from dungeons.
e.g Speed up, Vitapods, Vials, Gun speed increase, Gun damage increase, etc. I would make the increases stack, say like a gun speed increase would make a gun increase but 1 point, but if you have 6 its at its maximum.
Post what you guys think below. Negative feedback is just as good as positive, so I don't mind any non-supporters cos hey? Not everyone likes Black Ops.
This could be the next best thing for Krogmo.
It would basically be like Horde mode from Gears of War. There are more examples but this is one of em and I get the general idea of what you're suggesting here. Let's say that there are 3 different tiers for this game mode. Each tier being slightly more rewarding, but more difficult than the others. You start fighting enemies and such, and they all get harder every round. They could also re-introduce enemies like Tortodrones, Sloombargo, the Oiler Baron, and the legendary Vog Cubs.