I really like this game probably better than the experimental version, actually. I just have some things to suggest: For the frost fire, does it actually only slow down enemies for 1 second? (when it is not upgraded) because even right when you get the upgrade, the enemies are still encased in ice after 1 second, so could you make the ice go away after the certain amount of time?. Also, I have 2 ideas for new upgrades that you could add. 1. An upgrade to get bigger fireballs, so that they can hit more enemies at once, and possibly do more damage. Also: just an idea you could make it like when the fireballs are big enough, they create craters, like a meteor, they does more damage or maybe slows enemies down because they have to walk through it. 2. This upgrade would probably be really good, so I think you could make it one of the purple upgrades that appear on lvl 60. (it only appears on lvl 60). Hypnotism, so enemies can attack each other, and maybe they do like 20% of damage they would do to the wildfire.
Please consider my ideas! Also if you do add them in, can you also add them in this version? I play this one more so I'd prefer that. I know you said this version is like a year and a half old, so...
anyways, bye!