Cant start the game because of the message: could not find Unityplayer.dll some tips how to fix that Problem?

Im having this problem, everytime I  try to open it or show it in folder it gets removed, any tips?

i think i know what youre talking about.

you need to open the karlson exe file in the same folder as the other files. idk why but thats what works for me.

i had the same prob but its easy to fix. either karlson in the folder or drag it karlson folder to unity and click open with or vise versa