Created by Storyyeller. Unusually for fangames, it was written from scratch in C++, rather then using an engine such as Game Maker or MMF2. Due to the different engine and differing design philosophies, it contains a number of differences from most other fangames. It is also the only fangame designed to easily support Speedruning, with built in features including savestates, replays, and single frame advance.
I Wanna Be The Ultimatum
Created by Matt and Kyle.
Fangame The Game
Created by VertigoElectric. Notable for being the only major fangame to be created with MMF2. Also, the mouse kills you. Unfortunately, it's been in Development Hell for a while. In addition, it isn't really a fangame, it's more like an "inspired by IWBTG" game according to VertigoElectric.
Created by Rogelio Díaz, in a tribute of a venezuelan blogger named Angel David Revilla (Dross Rotzank). He writes the blog "El Diario de Dross", a very sadistic and black-humor diary in spanish language.
I Wanna See You Suffer
Created by UltraJMan, who started creating it following his hellish, rage-inducing run through I Wanna Be The Fangame, and it is far more sadistic than IWBTG or IWBTFG. Currently in its alpha stage, it starts you off on an agonizing descent through a spike tunnel that you will spend at least a few dozen tries getting through and it just gets worse from there. One only wonders what JMan was thinking when he made this. He was getting Revenge on everyone who encouraged him to play IWBTFG.
Created by Solgryn. Like Fangame, it was also created in MMF2. Contain gratuitous swearing, and lags horribly on some computers, but is quite fun otherwise. Also worthy of being one of the most visually stunning fangames out there.
Created by Dakaarts. This game replaces The Kid with Mega Man and also borrows a lot of influences from his franchise. It doesn't have quite as many cheap tricks as most of the other fan games, but it's still pretty insane. It was unfortunately abandoned in 2013.
Tropes Common To Fangames in General
Creator Backlash: Tijit, creator of I Wanna Be The Engine, and Yosniper, creator of I Wanna Be The Better Engine, have deleted their engines and tried to have all postings of them removed or banned, due to the numerous crappy "fangames" being made with them.
Follow the Leader: There are many, many lesser known fangames, especially since the release of Tijit's I Wanna Be The Engine.
Playable Menu: Of course, if the game doesn't throw ya into the first level straight away. Naturally, the menu CAN BE the first level.
I Wanna Be The Better Er- Engine not only allows players to select difficulty on the first level. They also can remap the controls right there.
Sturgeon's Law: Unfortunately, the engine makes it easy for people to attempt to create fangames, regardless of whether they actually have any skill. This even got to the point where the creators of said engines decided to remove them from the forums to stop the horrible fangames.