I was interested in Kayin's ability to fuck with people in IWBTGG and I wanted to be able to do the same thing. Over the summer I made a tool called I Wanna Fuck With The Guy. It is essentially a list of commands (and their arguments) that you can use to set up a server to fuck with someone in IWBTGG. All with an easy-to-use GUI

Most useful commands and entities have been discovered and added and it is very easy to add more, since IWFWTG uses XML files. The only limitation is that the computer of your target must have a modified hosts file that redirects all requests going to gamejolt.com, to your server (IWFWTG has an option to easily modify the hosts file to do this, and revert it back).
You can download IWFWTG here:
http://pennycreations.zymichost.com/iwfwtg (make sure you read the guide).
There are some screenshots in the guide:
http://pennycreations.zymichost.com/iwfwtg/guideHere's one of the main window (from the guide)

Here's one I took in-game after spawning some things (the spike wall is slowly moving to the left)

IWFWTG allows you to move around and zoom in/out on images of each level. It makes it easier to place entities (like the spikes in the pic above), since you just double click on where you want to spawn something.

You don't have to use the buttons on the right. There are keyboard shortcuts, and the mouse can be used as well.
(Note that the starting point (0, 0) varies depending on which entity you are spawning. For example, (0, 0) on a ground tile is the top left, but on a spike it's the bottom left.)
Edit: As of version 2.30, when using the level click-for-coordinates map, a rectangle the size of the entity to be spawned will follow your cursor (it will also be anchored at the entity's proper origin). The entity marker will be the actual size as well. If the entity can rotate, you can rotate it by holding CTRL and pressing any of the zoom keys. Here's an example, with a spike:

You can do other things like reverse the controls, rotate the screen, enable curse mode, etc. Spawning stuff is just better for screenshots.
Any feedback is appreciated
