Here is a tip for zattikka or any other one which has identical rows: zoom in a lot on your browser and look for faint gray-ish lines on the columns and try to get those lines to fit together.
I feel that there is 2 things that could improve this game: 1 - The game would do well with a map, especially for hardcore mode so you don't have to remember where you left those 2 enemies and guessing wrongly and losing some of your health from an enemy you need to go through. 2 - This is more of a personal thing but I think it would be nice to have a way to rewind a bit if you made a mistake. Still though, this is a great game and I would highly recommend it.
I have to say that in my opinion level 22 is BS. I don't know if i'm missing something but i found that like 99% of the time you just die no matter how fast you try to rush through.
for me, the O buddies had enough and managed to stop the Xs before they could even kill one of the group https://imgur.com/rSPCLSR (seriously though this is a bug)
 "A"){kind=icon}
 "Ordinal Markup"){kind=icon}
 "Idle Lottery"){kind=icon}
 "Pixel Shuffle"){kind=icon}
 "Magirune"){kind=icon}
 "Unfold"){kind=icon}
 "The Value of Time"){kind=icon}
 "Have you missed the TUTORIAL for LIFE?"){kind=icon}
 "Idle Hacker"){kind=icon}
 "NGU IDLE"){kind=icon}
 "Tough Growth"){kind=icon}
 "It's Just TIC TAC TWO"){kind=icon}
 "Gimme Potato"){kind=icon}
 "Super Mighty Battle Quest"){kind=icon}
 "N3wton"){kind=icon}
 "Swarm Simulator: Evolution"){kind=icon}
No one actually knows.