This is a good puzzle game. The controls work just fine. Great 8-bit style RPG sprites. The bleeps and bloops are amusing, and the music sounds great. The different character classes using unique attacking ranges, and on the grid layout, reminded me a bit of Shining Force.
The puzzle mechanic is pretty creative. I like how it's necessary to collect life forces in order to kill stronger monsters. Rather than just figuring out who to move where and what spot they can kill a monster from, you must figure out how to kill monsters so their life forces land in the right direction, then figure out who, in a single move, can collect enough of them to kill one of the stronger monsters on the board. I also like how the life forces stack when more than one lands on a spot.
The ending is chilling. Great zero-hour twist gives the game a pretty good little story. There may even be a lesson there.
Some issues: the game is somewhat unbalanced. I found it to be far too easy for the first 20-25 levels, and then suddenly, 26 and 27 were exceedingly difficult. The last level was only moderately tough.
However, you're in need of a longer tutorial. Things get confusing pretty fast when you don't explain the properties of the different units, and it did take me a few minutes to figure out how the numbered enemies, the life forces, and the characters levels all fit together (even though you do explain some of the early on). All of the this can be solved with experimentation, but if you added a little more information about how the characters work, you could take the opportunity to develop the story a bit more.
All in all, an enjoyable game. What you have here is very good, but a few tweaks and a little more information could raise it to excellent.