An OK start to a game. Doesn't feel finished. graphics are glitchy. Gameplay is either buggy or inconsistent. I pick things up, I have no idea what they do. I touch monsters, sometimes it kills them, sometimes it just pushes them around. Fire heads shoot fireballs, but they don't seem to affect me or monsters or the tree or anything, really. Once in a while the level reset, I guess because monsters ate the tree. But sometimes it happens when no monster is near the tree, so no idea what's going on there.
Nice start to coding a game, but needs instructions and to be less glitchy. Also it would be nice if the player moved faster, and wrap the screen so when you go off one side you appear on the other side.

Please be clear about your controls, you show say it in-game or in the description stuff like how to move, jump, how to shoot, or what that "F" counter means in the corner. Shooting mechanics aren't clear because sometimes it shoots sometimes it doesn't, I'm guessing those blue sprites are used to "charge" a shot but occasionally it doesn't shoot, if you can hold only one charge at a time it should say so.

Controls I've figured out so far:
WASD/Arrow Keys - move
Spacebar - Jump
LMB - Shoot (in the direction you're facing, doesn't shoot towards your cursor)

Some bugs that I found:
-Enemies don't die, both zombies and fire spirits (I touched and shot at them and nothing happened)
-Tree doesn't die when HP is 0, when I refreshed the game the bug was gone
-Zombies that don't die and is pushed far from the tree will continue to attack the tree until the tree's HP is 0
-Fireballs don't do anything, doesn't affect me or harm the tree
-Sometimes the things spawn within terrain, but I was still able to get them

Hopefully you can tweak around this game and fix some stuff because this can be a great game, there are just some problems here and there