Damn, thanks for the thorough review
When you press the stop button, the first reel will stop nearly instantly, the rest are up to RNGesus. So you're not exactly in control, but timing the first reel right can be a difference between blocking and hitting Spike with a Beetroot. I understand why this is not clear though, and a better tutorial tooltip is needed. Rusty Cog just lets you time all of them, which lets you pretty much select each turn by hand if you have the patience and enough eye drops.
I haven't "beaten" space invaders ever, that game is kinda unfinished as I'm on the fence about it.
The crash you got probably has something to do with the Perfume item since it appears to be activating, thanks for reporting that
As for the color balance:
It wasn't my intention to make mono colors the best, but they are the most consistent due to how matching works. However, going into one color should hold you back in some other areas, as the only color that has access to everything is Purple, but that has its own problems. My ideal outcome of balance would be that builds focusing on 2 colors, or 3 colors with strong duos, end up being the best. I'm also trying to add enemies, especially bosses, that counter specific weaknesses in builds. For example, if you have no Blue at all, King of Clubs will slap you down. If you have too much Red, Spike will out-retaliate your damage. If you have a meandering slow deck, Queen of Spades will end you. There's a boss in chapter 2, DJ, that gains strong color-themed buffs that can only be removed by activating that color, meaning that a mono-colored deck will only be able to remove one of the five.
Admittedly, I probably haven't done enough to deal with Green. The only thing that comes close is Chieftain boss, as he purges Poison off when it goes above 10, and since Poison is just a single instance of damage per turn, a Shell will negate it. But he's a Chapter 1 boss so if you can get past that (or just happen to see Malfunction instead) you're fine for the rest of the run. I should probably give the debuff purge action to a few more enemies.
I have not designed final bosses yet, so I might aim to counter mono-colored decks with them.