This game is on an extremely short list of games I felt inspired to reach 100% completion with.
It's puzzles are incredibly difficult in some cases, there are almost no instructions, just experiments with your kirby-like powers and mazes to explore.
Some things I never fully understood like the big flower energy balls, but even just looking for hidden areas like you're back in Wolfenstein 3D can be addictive habit in this world.
The music, simple but beautiful character and world design create an experience that's incredibly satisfying, provided you aren't showing up for fast-paced action and gun fights.
You'll end up spending a lot of time youtubing things you can't quite wrap your head around, but the answers are out there if you need 'em!