The core concept here is neat. I figured a handful of collection range upgrades + basic attack upgrades + ring of fire + some magma fireballs for extra clearing. Ring of fire in particular is probably responsible for some 99% of enemy deaths.
One annoyance is how you can't figure out the additional elements other than with trial and lots of error, and you lose your elements in the process; the reason why Doodle God works is that you aren't really punished if you don't find out a correct element (and it also had hints). I would prefer if you didn't lose the elements or if any combination you already tried would become disabled. On that note, a UX nitpick - complex elements that ran out no longer have "Create" RMB button working for them. Either way, I found Steam/Cloud/Snow/Mud/Magma and I haven't noticed any other elements combinations, despite seemingly trying all combinations (Snow in particular seemed like a dead end).
Also, while there were quite a few upgrades, many of them boiled down to "stack an attack performed every X seconds". Aside from the general damage + fire rate upgrade and collecting radius upgrade, I'd like to see more upgrades directly affecting the player character and main attack, e.g. health restoration or chaining.
One more thing: it would be nice if triggering the upgrade screen also caused some knockback near the player, so that the player doesn't end up returning to the main game too abruptly.
The artstyle is neat and mostly clear regarding what happens in the game (though at some point the enemies swarm so much the player doesn't have particular strategic decisions left). The music is fitting. At some point the game lagged, though I think that's a given once you advance far enough in this genre (especially with web builds).
Pretty nice overall, but I feel the element upgrades system could use some extra UX love.