Love the game. Very nice work. I think the countdown timer for boss levels is a little too aggressive. I click almost as fast as possible with very few mistakes but don't see a way to complete the larger maps, starting with Stage 3. Also, it seems like artifacts can only be used once per round? Any harm in letting players use them until all charges are gone? To balance the artifact that gives you a free toy each turn, perhaps have it only provide a 1-charge artifact. Great job overall.
Yeah, all the boss modifiers will be adjusted in the next version, and the countdown will be fixed. Right now it works fine in the early stages but feels too strict in the later ones.
Artifacts will also be reworked just like you said, charges will represent the number of uses. And here's a little spoiler: I'm thinking of letting players select an artifact before starting a run that sticks with you for the whole session, basically becoming like a character choice where the artifact defines the ability.