Picross S can be played by up to 2 players, so they can technically solve boards twice as fast.
Seperating runs from 2 players and those from 1 player would be the most fair imo.
PS: as a sidenote, would it be okay to use the game's notation of levels? P001 - Key for example. /edit: after playing for a bit longer, it seems like the Mega Picross don't have any new pictures, only re-arranged them - so just the name of the picross is enough for the listing, and the amount of ILs could be cut in half (300 -> 150) by using categories to distinguish between regular and mega. like 1 Player | 2 Player | 1 Player Mega | 2 Player Mega
~HDK
Sounds good. Though the mods have been inactive for 11 days/1 month so we'll have to see if someone else can do moderation if none of the current return for a while.
I'll try contacting them.