Really enjoyed this! The aesthetic is really interesting, and I love the colors used. The use of the isometric board really works with the gameplay as well, as do all the sound effects and music. The characters are cute, and I like seeing their faces as they get more hearts. I didn't play all the levels, but the first 3-4 were interesting with the perfect amount of challenge for a puzzle game, and new mechanics were introduced at a nice pace.
Talking about the core mechanics: love them!! Puzzle games are real tricky to get right, and I enjoyed this more than many fully released puzzle games I've played. Would love to see you take this farther.
There were a few small UI things that I noticed that seemed off, but fairly easy to fix. I'll mention them here in case it's useful.
- The "FIRE" button is kind of easy to accidentally hit when placing hearts on the corners -- moving that up just a bit would really help
- When the different types of hearts are on the game board, they're visually a little too similar, making it a bit harder to differentiate and plan
- Took me a while to realize I could only fire the hearts once -- having some "restart level" dialog pop up after firing and not completing the level would help out with this
- The instructions say you can place hearts in the dotted boxes...but all the boxes seem to have dots! Having a little more clarity in the instructions, along with possibly a visual aid could help there
- I like the shortcut keys, like R to restart, but having physical keys represented on the screen as well is nice for those that may be less familiar with using shortcut keys
Overall, extremely well done! The trickiest things to get right in a game like this were very well executed.