Can't die? *deletes from purchase list*
I remember a Wario game I have on Gameboy where Wario would never die, just get set back some on the level you were on. Need to see what that exactly means.
In regards to the game, I am getting amazed at the sheer variety of things you can do and the likelihood of tons of hidden stuff. Feels to me what Super Mario Bros. was like back in the day.
Wario Land II and III had Wario as functionally immortal, but not invincible. So if you got hurt, there would be recoil (possibly ruining your jump or something to that effect), and in Wario Land II that meant lost coins until the count hit zero, then nothing.
Yet those games were challenging enough in their own right. It's all a matter of mechanics. Certainly if you just turned death off in, say, Resident Evil, it wouldn't be challenging, but you were meant to die