Congratulations to this nice entry. Interesting game and concept that has potential. Really liked the overall style. I try to give you some feedback but i'm not an expert for this kind of games. Dont take my words too harshly, i know there is limited time in a jam and its ment for future development (if you wish so):
For me it felt like there is a little bit too much randomness involved which makes balancing for such a game pretty hard. - Depending on the randomness levels could either be pretty easy or extremely hard (i recognized that the overall numbers increased over time but placement and spread felt pretty random). - You could get really good cards as reward or only decent cards or even the same cards after finishing a level (for example i got the choice between 1 card to add 3xGrumpys and 1 card to add 5xgrumpys, so its clear what you take). - And even the cards themselves had randomness like removing random animals or rows and stuff. As a player i whish i had more control over the outcome.
Suggestions: - Probably create some currency like gold that you earn by securing your tiny creatues. - Buy cards/rewards with your gold (have multiple tiers of cards with different costs and give the player 1 card out of each tier. You could decide if the player can only buy one card or all three if he has the gold) - change cards to give the player more control instead of pure randomness. Instead of removing a random row, let the player select a row at the start of the level (and so on) - I would probably create some pre-defined spawn patterns that you combine to build levels. Have easy patterns, medium patterns and hard patterns and combine them to create levels of different difficulties.
Overall a great job on this game with a nice base concept!