I agree that the main game is the most important thing. The challenge mode seems like it could use a little polish as well. Although I stink at it so what would I know, lol. Polish will probably happen along with the rest of the game. I just love that the game has one. Heck, I'd like to have a few challenge modes!
I got Ambush as a ? reward from the foundry. That was cool. It brings me back to a point I made earlier on how I'd like to see the ambush mode pop up on you. Or kinda feel like an ambush. It should be deterministic to be fair in competitive play. But I like how in Star Wars it felt kinda random. I've gotten better at looping the flip down scoop shot on the premium/le. It's pretty awesome when you get a few in a row. But, I was thinking that maybe some of the other modes in the game could contribute to qualifying Ambush mode. I believe it take 5 count ups to qualify. Maybe every two missions completed will advance the count up by 1. Every level 3 encounter advances it by 1. Razor Crest modes advance it by 1. This could be done quietly behind the scenes until BAM, you've qualified Ambush!
Just a thought. Fun game, it's a keeper.