This game is interestiong, facinating and mysterious.
To begin, the title. REDDER, that's a palindrome, and it's Dutch for 'savior' (that has nothing to do with the game, just a fun fact).
I got all the medals, including the secret areas, and those were rather interesting too. At first, they were all underwater, with a scenario very different from the rest of the game, and they all showed a word in the wall. One word was 'ANNA' which is a palindrome, AND your name. The others contained the words 'PART' and 'TRAP', which are palindromes of each other. I found that strange, it gives me the feeling that there's a hidden message.
Then, the gameplay. At first I was like: 'This is impossible!', but as soon as I collected the first gem, things became a lot easier: the more gems I collected, the less hard it was for me to collect the others. You just must have the skill to understand the puzzle.
A very interesting point, now: the glitching. I think I noticed the first glitch between 5-7 gems. You're lucky I didn't write this review when I was still playing the game, because then you would've gotten a 5 or 6 and me saying 'Omg, there are glitches everywhere!'. But I think I understood the message. The more gems I collected, the more the game started glitching. This, according to me, must mean that collecting the gems is bad for the planet and destroys it. But I started to hesitate about that when I collected the last gem: everything turned block-like?! No music, only creepy sounds, and all characters were either lines or blocks! I don't know what this means, but I'm sure it does mean something.
I also found a glitch that was NOT on purpose: the character is sometimes unable to jump. This only stops when I die, warp or proceed to another screen. I would be glad if you fixed this. Other than that, very good game, deserves a sequel.
Also, to all the other users: sorry for the spoilers.