Suggestions:
1. Make the game window smaller, it's just too big.
2. Reduce the number of lives, it's just too many.
3. Don't add upgrades, or anything to make it fun.
All joking aside, I can't say if this game is fun or self inflicted pain. Clearly a lot of thought went into the level design. But trying something 100 times just to see if it can actually be done isn't fun for me.
I played the first couple levels, it's very polished, even if some of the controls are hard to see. But the puzzles were very simple, the entire difficulty seemed to be the control system, I don't see that being fun later in the game.
leveling is seriously flawed, author needs to pay closer attention to gemcraft 0's implementation. Basically you can level all the way to max skills just using the 1st level over and over. The bonuses really add up once you get them.
Nice mash up between gemcraft and phage wars. A lot of questions and some bugs. One thing that seems quite counter intuitive is how is exp calculated? Seems winning the easiest level over and over is the quickest way to level. I've tried zombie on the same level and got less, harder levels, got less.
Flying more or less horizontally above the table, there seems to be a 'path' of corn. Just try to hit every one, and hit detection is pretty loose. I'd not give this a '4' since there are no upgrade, little depth.
Demo version, can't leave the 1st town. I lowered my rating, I'd expect at least the first 3 "horse" towns and full disclosure to have given the game a higher rating.