I got the achievement for finding all the health upgrades even though I still had at least one left. I also got the achievement for not getting shot on the battlefield, but I most assuredly did get shot (almost died too). If it means to say to cross the battlefield without attacking, then that would make sense. Also, I feel like the achievement to kill the boss with only freeze potions is a bit impossible. Technically it's possible, but in reality, it's impossible. I would use my potions, but if I die, they'll just be wasted.
So I walked through the poison on the tech planet after fortifying my health and I was able to pass through with no problems. Not sure if that's suppose to happen (I later discovered a potion for clearing out the poison). It'd be nice if you could go to the crafting recipes and hit a craft button from there instead of constantly having to put the ingredients in manually. Also, I got the achievement for making all the potions, but I never made the speed potion (never had a reason to).
Only thing I dislike about this is that I can't continue after beating a game. Usually games like this let you. I got over 3000 stars the same round that I collected all the parts, so I was unable to get that ultimate weapon thing.
I found it a bit difficult to drive the car which I drove straight to the helicopter (I didn't want to leave the safety of my car). First time I played I was scared. The second time I explored (and found a new gun).
@nivq You use the jetpack at the beginning of a level. Before actually starting the level, you have to "purchase" it with gas at the bottom of the screen where you can purchase abilities with gems.
After beating episode 2, I opened a crate that gave me all of the special abilities, and then I got more health. Beat episode 3 my first try because of it.
I played the first one right before playing this. I was wondering what the writing on the wall meant. Then I found the tiger plushie. I saved a kid's life.
For skills, you should probably change the descriptions of the skills that increase your chances of getting double coins or potions. The way they were worded, I thought they Increased the chance for every kill. You should probably change them to something like "n% chance that an enemy will drop 2 coins/potions instead of 1."
I liked it. But then I got stuck. Then I found the second part of the key and started moving along nicely. Then I couldn't find the last two mirror pieces. Some of the things in this game weren't thought out very well as to where they were placed. Unfortunately, that happens a lot with games like this.
I have a love-hate relationship with the tombstones. I love them because I like to see what they say, but I hate them because I just had to die to everything I saw.
 "Sentry Knight"){kind=icon}
 "Zos"){kind=icon}
 "A Bonte Christmas"){kind=icon}
 "Zombies Ate My Motherland"){kind=icon}
 "Deadly Road Trip"){kind=icon}
 "Undead Isle"){kind=icon}
 "Cyber Chaser"){kind=icon}
 "The Last Door - Chapter 2: Memories"){kind=icon}
 "Deeper Sleep"){kind=icon}
 "Deep Sleep"){kind=icon}
 "Cursed Treasure 2"){kind=icon}
 "Battalion Commander"){kind=icon}
 "BNKR"){kind=icon}
 "Viktor the Nth"){kind=icon}
 "The queen of snakes"){kind=icon}
Yah, it's always better for your health to go on foot.