Thanks Teruri, glad you liked it.
Yeah, stage 4's opponent is none other than the infamous Roguefrog!
I've been drawing him and the character from stage 2 for years. They were originally spin offs of Muppet characters, but due to my art style's continuous development their appearances changed drastically over the years to the point now where some of them hardly resemble their original molds. So now they're characters of my own. There's 2 other characters that usually accompany them in my paper RPGs, but I couldn't include them in Supa Pong because they look
way too similar to their muppet counterparts.
EDIT:
Funny enough, stage 4 is the only one with a hidden character in the current version. I intended to include more, but my family and friends who agreed to draw them haven't finished yet, so they'll be included in 1.0.1. My sister drew level 4's alternate character.
Oh yeah, you can play against alternate characters by typing "zzz" on the stage select screen in Freeplay. You'll hear a beep to confirm that you entered the code correctly. Once activated, clicking on a stage will bring you its alternate form.