Actual addiction.
+ A problem is presented. A solution is made - by you. The solution is deployed. You unlock the next problem. You realize your previous solution needs polishing. Repeat.
+ Excellent sound. Atmospheric noises to study/sleep to.
+ Huge QOL improvements since launch, and it just keeps getting better.
+ The huge amount of community content ensures that even when you finish the game and assorted challenge runs, you will Never be done.