Finally beat the game! I tried about 6 - 7 times!

The game play was cool! simple and fun!

However there is a little bit not balance!

Strength Upgrade is the MUST and you just need to MAX it and you can easily beat this game
I try to upgrade the second skill first but I found that there is no way to survive if I do that!
It's because the grey rat are already spawning, some of them will straightly go to my base and I have no way to defend becasue I don't have enough Strength!

Overall it's fun!! I have a good time :D

Very fun game, played it for over 20 minutes trying to beat it, you struck a pretty good balance between it being hard but not being too unfair.
That said some thing definitely need an improvement:
1-The instructions aren't quite clear, it could use a little tutorial explaining stuff.
2-Every now and then, when I catch a rat or a mouse they just disappear
3-The order of the symbols in the UI and in the requirements is flipped, so I got contantly confused about what I actually needed. Having icons next to the requirements rather than names, and having them in the same order as in the HUD would definitely help.
4-at the beginning, it often happens that mice spawn in the bushes and start heading away from the level, resulting in long stretches of almost no mice until the rats appear, at which point you quickly lose your battery.
5- the upgrading menu definitely could use some icons, and a bit less text for the first 2 tries I had no idea you even could upgrade your crow/base, only on third one I accidentally pressed W, and then tried to click on those boxes.
6-The shield limits aren't well defined since it's a gradient. Having an actual circle instead would help.

All in all, it needs more polish, which I guess you ran out of time for.

Other than that I had loads of fun, The idea of having a battery that gives you a second shot is a great boon for first time players, and once you understand the mechanics of the game the core game loop of upgrading, grabbing enemies, collecting resources, recharging and crafting.
I wholeheartedly encourage you to polish this up and release the game on a site like kongregate or ithio.

The game is fine but I did not understand why I could not pick up the rats and that there objective. The concept plagues me to continue

I liked that the game was very easy to get into, the follow mouse function got pretty "slidy" at times were character did not follow mouse. Other than that it was an easy way to control(would fit great as a mobile game), the whole recharging and gathering food was fun! I know sound is pretty hard to make, but you could consider using a sound generator like BFXR for the next jam, make things a bit more interactive with sound effects and doesn't take much time ;)