BUT gacha wise it's pretty good actually, the artstyle also looks good
also this game doesn't really have a story so-
The effect and music can also make it pretty engaging.
However, I find that it had fall short when it come to designing obstacle.
For example, there is tile that cannot be remove, that deal damage and a few others.
Most of it is not solve by you but rather by using compatible unit.
A nice puzzle game usually increase in it complexity. However, crash fever attain increased difficulty by jacking up enemy strength/potency.
For example poison that kill you in a shot. Or 4/5 of board filled obstacle tile.
All of it was solved by having specific unit to remove the negative effect, with newer stronger unit introduced constantly.
While it have a puzzle like setup, Crash fever is a RPG game with constant introduction of new unit and not a puzzle game.
Lastly, the game is very grindy for there is emphasize in getting 99copies of same unit