You might not have played Treasure of the Rudras (SNES)

Treasure of the Rudras (Rudra no Hihou) is a JRPG by Squaresoft from 1996 that was never ported to english, but received a fan translation.

Gameplay: JRPG, Single Player
Treasure of the Rudras is one of the older Squaresoft JRPGs. It has a rather simple save the world storyline but also a lot of unique features.
First off TotR has 3 storylines you can/have to play through. Each story follows a different group of heroes on their personal quest during the "last days" of the world. Sometimes these groups meet, but usualy you will only see the results of actions the other groups did at a certain time in the story. Spells have to be learned from people/books in the world or 'guessed' and then written down inside a spellbook to be used. This feature is particularly interesting because you can use the player knowledge you gained from one storyline while playing the other story lines.
The 3 storyline structure also helped in making the game have a lot more content than would normaly be possible on a SNES cartridge. The different groups go to the same locations at different times during the game. That allowed the developers to reuse the same art assets, but change up the map for different gameplay. In one instance a cave that has been visited by 1 party is later explored by another; the second party finds the cave flooded with water though, which changes the caves layout significantly.
All in all a very interesting game I would recommend to everyone who likes JRPGs.

Get the Fan-Translation here or test in an online emulator.

You might not have played The Whispered World (PC)

The whispered world is a point and click adventure from Daedalic Entertainment that was released in 2009.

Gameplay: Singleplayer, Point&Click Adventure, Humor
The whispered world is not your standard lighthearted pnc-adventure, but instead features 'Sadwick' a pessimistic clown that does not live the easiest of lives. Nonetheless some humor is still in this game to lighten up the mood from time to time.
You start your journey at your circuscaravan, where you have to do chores by using standard combination techniques. Your pet-snail Spot will be a vital help for whatever you have to do and will even learn a few tricks along your way.
To grasp the story without too much spoilers, watch the following trailer. Saying one word more could spoil the fun, but be aware the story is good.

Take a look at the first minutes of gameplay to get a feel for the game.

The game can be purchased on Steam and gog.
Also keep an eye out for Whispered world 2.

You might not have played Lands of Lore: Guardians of Destiny (PC)

The second part of the Lands of Lore series that was released in 1997 for the PC.

Gameplay: RPG, Story, Singleplayer, First Person

You are Luther. You have been accused of being a servant of the dark armies and imprisoned. You manage to escape because you are cursed to randomly transform into a tiny lizard or a huge demon. This curse is also the reason for the accusations. After your prisonbreak you will have to find a way to break the curse. 

The Game features a variety of different magic abilitys, weapons and mechanics due to the curse that lets you either be a tiny lizard, which enables you to go through small passages, or a huge demon, that can destroy anything in its path. The controls in this game are a bit iffy, as you will have to click on a button with your mouse to attack or cast a spell. But the game does not suffer too much from that considering the gameplay is not all about combat. A mayor part of the game is interaction with your environment to solve puzzles and that works like a charm with the mouse controls.

The game is fully voiced and has a quite charming retro soundtrack.

You can get the game including the first part of the Lands of Lore series in a bundle for 6$ on gog.

You might not have played Geist (GC)

Geist is a unique first person shooter released in 2005 for the Nintendo Gamecube.

Gameplay: First Person Shooter, Singleplayer

Ever wondered what it would be like to be a Poltergeist and possess objects and people? Well you can get a glimpse of that in this game. You play the role of a scientist who's geist gets extracted in a top secret science facility he is infiltrating. They try to brainwash your ghost into a soldier for their cause. During the brainwashing you get rescued by the ghost of a little girl and from then on try to use your new found powers to stop the organization behind all that.

The game features some minor puzzle elements but for the most part succeeds to be a very good first person shooter with a great atmosphere.

An assymetric Multiplayer Deathmatch mode (Ghosts vs Soldiers) is available and quite fun, but because of splitscreengaming you need a pretty large television to have fun.

You will most likely be able to grab the game for cheap on Amazon.