It is fun. In the future, I expect a full scale auto-battler from you. But of course there is some room to improve.
Pigs tend to leave the screen or disappear when they are dragged at times. Power scaling seems to need balance. It was easy until 23 after figuring it out but merging cause a big loss in overall power it seems, so I have lost in wave 26. At some point, they die too easily, even at level 4 against level 3–4 wolves. Even though I have filled the battlefield with them. I think their base stats are a bit too high and their merged power is not strong enough. But yeah it had to end at some point, or I would keep playing until I reach 100, probably. Also, it would be great to see more color changes after reaching purple. It is addictive to see them growing like that. Finally, need either a more chill music or just full action. Depending on the mood you wish to achieve.
Overall it was pretty good. I couldn't stop playing.