I agree. There were very few platformers with so nice AGA gfx (also Quik the Thunder Rabbit was AGA and impressive) unfortunately, and that's why it's a pity for Oscar...
Would be great if you can add those features (if we're lucky there's a sort of "respawn countdown timer when-out-of-screen" to alter?)!
For big enemies I'd leave it optional, but I agree and makes sense a pair of hits.
Levelskip complete key (optional please, I hate to cheat accidentally!) is also good.
P.S.
There is still that small glitch underwater with rattling up/down sprite of Oscar at bubble sound to fix BTW