(I'm back) In order for lv 21 and above to be of some use, I decided to add "Upgrade Cards". This will allow you to choose what you want to improve, but each card has a limit (that's the downside). They will only appear when you raise lv 21 and above.

Underworld Frisk

Core Frisk

Clover

Dusttale Sans

Sans at the battle (remastered)

Battle system (This is how the battle system might look like)

Health Bar (for monsters) (+ sprites for monsters that I managed to make (3 + hard mode)).

The chances of monsters appearing:

Normal: 80%

Hard mode: 20% (after lvl 10)

Flowey the flower

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