Level design

VGMaps - The videogame atlas

Noclip - Map viewer

Map Genie - Awesome Interactive Game Maps

LEVEL-DESIGN.org - Reference Database

Level Design Compendium

watabou - Medieval Fantasy City Generator

Rayman map archive

Game & Level Design Tips, by Tommy Norberg

How to design levels for a platformer

Game Maker's Toolkit - Youtube

The Level Design Book

Interactive tutorials for math and algorithms - Red Blob Games


Editable list - Google Drive