I Wanna Be the Guy/Fan Games

I Wanna Be the Guy has spawned a number of fangames.

I Wanna Be the Fangame
 * Created by Tijitdamijit and his friends. It is the largest and most popular fangame to date, and has been submitted to Moddb.

I Wanna Be The GB
 * Created by Ashimoto. Note: GB does not stand for Game Boy. Has been unofficially crowned by members of the IWBTG forums as the "hardest" fangame to date.

I Wanna Be The Tribute
 * Created by Shaman666

Pickory
 * 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.

I Wanna Be The Shrine Maiden
 * Created by holy. Based on Touhou. Has a sequel.

The Dross Game 2
 * 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.

I Wanna Be the Boshy
 * 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 and is currently the only fangame that has co-op play. Also worthy of being one of the most visually stunning fangames out there.

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.
 * Fan Sequel
 * 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.
 * Troll Fic: I Wanna Be the Guy doesn't have troll fanfiction, but it does have troll fangames. and  are some of the more obvious examples, though theoretically, any of the horrible fangames could be secretly trolls.