The game was fun although sometimes switching between eras wouldn't work.

Game looked quite cool. 

Once I jumped down the steps in the first part, where you meet the silver enemy, I am stuck since you can't jump high enough to get back on.

The feedback on getting hit could use a bump, I died once without realizing why; probably because of a bullet hit that I did not see.

Really liked the concept between switching to the different eras. :) Personally, would have been nicer with a bit more health as when switching to different eras, I would get "Game over" almost instantly. 

The idea is amazing! Sound effects are also awesome! If you could polish this game it would be really cool! Great job :)

P.S. I laughed when I saw the WW2 soldiers' pixel art XD So different from the player's pixel art.

I think this idea has some potential. I found it clunky to switch between time periods, especially when switching into WWII because I would hit something and instantly die. I think maybe adding some indicator of which time periods you should go to, or adding a check to make sure you won't instantly take damage would be good.