Have you been invited to participate in a game jam? These tools may be useful to your game development! 

NO TECH SKILLS NEEDED

Construct: Great windows only game dev tool that is free to use.
Game Maker: Very popular game development tool, tons of indie game devs use it.
RPG Maker: The latest versions are only for a trial of 30 days but if you download the older versions I believe they are still free. These tools are built just for making snes era rpg's.
Stencyl: Great tool for non-programmers, lets you create games with simple drag and drop tools.
Game Salad: Popular Mac only tool for making simple web and iOS games with no programming needed. Recently opened up a cool marketplace for assets.
Oh My Game!: Neat beta web based collaborative tool for building games. Still early but pretty good for an open beta!
Klik n Play: Classic game making tool for schools made for Windows 3.1. Still good after all these years and used for a monthly jam.

OHR RPG CE: Omega Hamster Republic Roal Playing Game Creation Engine. Originally created for DOS, this free system now works on anything FreeBASIC supports.

TECH SKILL NEEDED
Unity3D: Free to use game development tool that focuses more on 3D game development. Can be used for 2D game development as well, multiplatform as well.
Flixel: An awesome Flash game api that handles a lot of the grunt work for you, such as collision detection, particles, camera, etc.
Flash Punk: Another very popular Flash game api inspired by Flixel.
List of Javascript game api's: With the whole HTML5 movement javascript based game development is starting to become very popular... I have listed a huge number of libraries that are starting to become popular.
PyGame: Great api for building games in Python
Allegro: This was the first C++ game library I ever used, it's been around for a while and is still being updated.
SDL: Probably by far one of the most popular C++ libraries used for making indie games.
SFML: Another great C++ library that does ton of grunt work for you just like SDL.
Cocos2D: 2D api for building ios applications.
UDK: Use the free version of the Unreal engine.
Love: Lua based game development tool

Nuclear Basic/Fusion: A work in-progress game engine inspired by...
Blitz3D: A (now outdated) development system with a BASIC language.
Leadwerks: An OpenGL-based 3D engine that also has support for (and has the core written in)...
BlitzMax: A cross-platform "BASIC" language with OOP support.

Intel XDK: IDE/Toolkit for HTML5 app development. Has support for game frameworks (ex. Phaser.io) and mobile deployment/testing.
Phaser.io: HTML5 game framework with WebGL support, and other really cool features.
Haxe is now OpenFL.