Only three choices?! Fuck you!!
I picked:
Prehistoric. I really, really wanna see a stone age RPG. You can easily add fantasy elements in the form of having humans coexist with dinosaurs for maximum fun. Kinda like those old 60s action-adventure movies where scantily clad women and burly cavemen fight against awkwardly animated dinosaur puppets. It's such an underrated setting. In Civilization, my favorite part is the early game where you're discovering fire and the wheel and explore a hostile wilderness - early game of the Caveman2Cosmos mod is peak Civ. I also love that prehistoric city builder game Dawn of Man. The setting is not only good for strategy games, but also has potential for RPGs.
Early Antiquity. I'm a huge fanboy of ancient Mesopotamia and it's a crime that there are so few games focused on that area and era. It's the perfect setting for an RPG, most of what we know about ancient Mesopotamia is very mythical, their own understanding of history and the world was highly mythical, introducing fantasy elements would only make it MORE authentic instead of less. The gods can appear as actual characters who talk to humans through their statues and in dreams, there's a magic ritual for practically everything, there are tons of different monstrous creatures that can roam the wilderness... and also, high level characters can choke lions with their bare hands!
For the third I picked Renaissance, but I also put the Age of Absolutism in there. Both are fine. I'd really love to see something in the 16th-17th century. 18th would be fine too. The sheer amount of weapons available during that era would be awesome for a tactical RPG. In the 16th and 17th centuries they were so fucking experimental with weaponry, especially those wacky Italians. Everything was combined with guns, because guns are cool. Gun-swords, gun-axes, gun-maces, gun-polearms, gun-bucklers. There was even a multi-functional buckler that contained a gun AND a lamp for fighting at night. Crossbows were still in use too, and in some areas they used bows as well. Armor was at its peak too, with anything from classic chainmail to full plate suits to bulletproof chestplates available for the player.
Just look at this shit:
Now, while those were my three picks for the poll, I'd also love to see more games in other settings:
WW2 is such a popular setting for strategy and action games, I can't believe it hasn't been used for RPGs yet (except for two very sub-par Polish games nobody played). Especially when combined with fantasy. Something like the Return to Castle Wolfenstein setting would be PERFECT for an RPG. You got nazi occultist wizards, crazy scientists creating experimental superweapons, and a large selection of regular WW2 weaponry. I would, of course, prefer to play a game where you control a party of nazi occultists, but I wager the mainstream would prefer playing as the Allies opposing them
Both could work out very well. There already are some WW2 games whose scenarios would make for a great RPG, btw: the Commandos series comes to mind. You have a party of characters with distinct abilities and are on assignment behind enemy lines to perform sabotage and espionage missions. Peak RPG scenario right there. I can even imagine a C&C heavy WW2 RPG where you get to pick sides, or play both sides for a risky double-crossing game. Like an RPG set in Northern France in the 40s where you can either work for the Resistance or collaborate with the Germans and spy on Resistance members.
Modern day urban fantasy is underrated. All we got was VtM: Bloodlines, and since then, pretty much nothing. Late 90s to early 00s would be a better time for it than the 2010s though, before the advent of smartphones, because implementing those things in a game would be a major hassle. You can mix in some common urban legends, different schools of occult magic that are kept secret by their practitioners, and poser goth girls who pretend to be witches but aren't. You can also add in some crime fiction elements of course, because organized crime in a big modern city is always fun.
Basically just turn D20 Modern into a CRPG and you're good.