The Mono Hero might be the next character project I’ll undertake creating in SN, though he might end up taking a long while to complete.

I guess for some general lore though, he hails from a universe where everything in colour is completely monochrome, including himself. He doesn’t see through a filter, everything is genuinely coloured that way. Mono is perfectly capable of seeing in colour, not that he ever has.
Until now, duh.
The sky ripped into two one day, and through the apparent rift came polychromatic monsters of hellish origins. They demolished buildings and slaughtered civilians by the many, leaving no prisoners. Only one Florida man could stop them all, so he quickly put himself up to the task and started fighting back as a one man army.
I look forward to one day seeing him fully realised.

Totally Not A Doomguy Ripoff™