Hey, I'm looking for some new retro games to play. I keep on looking for some hidden gem but I haven't found any games I haven't played that are really something special.  Does anyone have any suggestions for games I should play here on the RGR?  I mean I have played your general franchises: Mario, Pokemon, Zelda, Metroid, etc, etc, but I am looking for something just a bit less mainstream that you think is satisfying. Well, let me know.

Ainstrings : Well, if you like 8 bit systems, there are plenty of great games for the Sega master system, the one I would recommend is one of the few asterix games on the system, the first one is probably the best, though. A lot of fun! It can be tricky at times too.

Sup Ainstrings. Looks like from the main ones you said that you like platform games. I'll try to recommend some of them as well but I am going to throw some at you from other types. Hopefully you'll find something in my suggestions that you like. Well anyways here goes and I'll say enjoy for whichever you choose. 
1. Ninja Gaiden Trilogy (platform)
2. Blaster Master (platform)
3. Solstice ( Arcade )
4. Dynasty Warriors Advance (Arcade)
5. King of Dragons (Arcade)
6. Splatterhouse (Arcade)
7. King's Bounty (puzzle,sim,strategy)
8. Gemfire (puzzle,sim,strategy)
9. Onimusha Tactics (puzzle,sim,strategy)
10. Advance Wars (puzzle,sim,strategy)
11. Monster Rancher Advance (puzzle,sim,strategy)
12. Silva Saga 2 (rpg) 
13. Brave Battle Saga (rpg)

Less mainstream?

How about.

Faxanadu?

https://www.vizzed.com/playonlinegames/game.php?id=287

It's a mythical RPG that is based of European, and Nordic mythology, like Lord of the Rings. It's not terribly hard and it doesn't keep you long either. It's realivly short compared to a game like the Legend of Zelda.

I say definitely give it a try. It does quite a few things right and I found it fun to play, though a bit easy.

I'll list a few for you:

Atari 2600- Dragonstomper (if it works here. RPG).

NES- Splatterhouse - Wanpaku Grafitti (platformer. A horror game/movie spoof); Nintendo World Cup (crazy sports title, like the NBA Jam of Soccer/Football/whatever you choose to call it); Monsters In My Pocket.

SMS- Nightmare Basketball (more crazy sports); Air Rescue (hard to explain).

SNES- Harvest Moon (RPG(no fighting)/Farm simulation).

Genesis- Toejam & Earl (this one is a genre all it's own. lol); Toejam & Earl 2: Panic on Funkatron (platformer. Nothing like the original); Bubba 'n' Stix; Wiz 'n' Liz (fast paced game that you have to play to understand); Shadow Dancer (Great game, but extremely unfair at the end of the game); Bonanza Bros; Trampoline Terror.

N64- Harvest Moon 64 (doesn't emulate well); Banjo-Kazooie; Mickey's Speedway USA; Tony Hawk's Pro Skater.

GB/GBC- Survival Kids; Harvest Moon 3; The Grinch.

GBA- Harvest Moon: Friends of Mineral Town; Lufia - The Ruins of Lore (RPG).

NGPC- Dark Arms - Beast Buster;

MAME- The Percussor (old school flying shooter); Knuckle Bash; Zupapa; Metal Slug; Namco Classic Collection Volume 2.

Sunset Riders - Similar to Contra, but not near as hardcore. Incredibly fun Western shooter. Fun on Netplay. (SNES, Genesis, MAME)
Avenging Spirit - Easily my favorite GameBoy game. You control a ghost, but you possess different characters. Lots of depth for a GameBoy game. (GB, MAME)
Donkey Kong Country 2 - You've probably played this game, but I'm throwing it in here because it's an incredible experience incase you've never played it. (SNES)
Banjo-Kazooie or Banjo-Tooie - Same as Donkey Kong Country 2. (N64)
Golden Sun - The best RPG if you are looking for the gameplay, not the story. Very unique fighting system. It has a lot of long cutscenes, but you never get so invested in the story that you don't care about the actual gameplay. (GBA)
Golden Sun - The Lost Age - 10 times better than Golden Sun, but it is a sequel so you'll have to play Golden Sun first. Possibly my favorite game you can play on Vizzed. (GBA)
Lunar Pool - Even if you don't like pool, you still might like this game. Easier version of pool. Fun on Netplay.

Like TheFadedWarrior said, Sunset Riders. Amazing side scrolling shooter, very fun.

Splatterhouse - any of them, violent, gory, beat em up, you can find the first game on MAME, and Turbografx 16, Splatterhouse 2 and 3 is on the Sega Genesis, and then like Eirinn mentioned, Wanpaku Graffiti is on the NES

Final Fight - A great beat em up that is on the SNES, or if you want to play the arcade version, play it on MAME.

Earthworm Jim - Fun platformer, crude, fart jokes, what more can you ask for

Altered Beast - Side scrolling action/beat em up, can be found on the NES, Sega Genesis, MAME. You beat the hell out of monsters, zombies, and all of that, collect blue orbs, and you can turn into Werewolfs, Dragons, Bears, etc

Ninja Gaiden - The older ones of course, but my favorite is the Arcade version of the first game, it can be found on MAME. If you want to play the NES port, that is a good one too. Great side scrolling action game.

There are plenty more too, plenty of awesome retro games.

I would suggest getting enough Viz for the Beta Test Ticket, then playing Sonic Adventure 2 for the Dreamcast, as it is by far one of the best Sonic games out there.

Have you tried the Fire Emblem games? They're pretty fun, all things considered. 

I also recommend Golden Sun and Golden Sun: The Lost Age! Both are pretty good, though The Lost Age is better.

And what about Donkey Kong Country 2? I know you said you'd played the mainstreams, so that's probably been done, but if not, try it. It's a lot of fun...and so is Super Mario World 2: Yoshi's Island. If you've not played that one, you really should! It looks cutesy, but it's more challenging than you'd think.

If you want just a good time-waster, try Kirby's Avalanche for SNES. It's a matching puzzle game and it's pretty fun. Good if you need a stress-buster break.