Ren & Stimpy - Stimpy's Invention (E) Game Genie
GAGA-GAGC
Jump higher (when standing still)
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Ren & Stimpy - Stimpy's Invention (U) Game Genie
GAGA-GAD2
Jump higher (when standing still)
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EDIT:
I noticed that the time that you're invincible after getting hit is noticeably longer in the European version. I compensated for this in the codes below. Codes for the USA and European versions both give you about 4 seconds of invincibility time. Staying invincible too long was problematic because if you fall down a crack or hole, you'll get stuck until it wears off.
Ren & Stimpy - Stimpy's Invention (E) Game Genie
H22T-GAC0
Stay invincible longer after getting hit
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Ren & Stimpy - Stimpy's Invention (U) Game Genie
T22T-GAAN
Stay invincible longer after getting hit