I'm not well versed in legalese, this game looks like it pulled assets from Koikatsu (or its mods) to make a paid game. Is this legal?

I'm stuck in title screen. I've already used mouse cursor; I heard the sound that it is moving over the choice, but I can't click on anything. I use the arrow keys and it doesn't work and I also swipe my hand the whole keyboard to check if any buttons should work on the title screen, but there's none ...

第一关怎么过？我十分怀疑这游戏没做第二关

イリュージョンに通報しといたわ

Completed up to level 31 (all 3 stars) but the only memories unlocked are levels 1-20.