First person template I developed inspired by retro FPS like Doom/Wolfenstein and dungeon crawlers.
Note that it does not have texture support, so you will only be able to draw walls with solid colors and fixed outlines. To modify the map, you can place and move "Block"s in the layout, but note that:
it won't work if the blocks are rotated, and
the bigger the block, the more likely you are going to run into z-ordering issues
Feel free to use it any project, and don't be afraid to hit me up on Twitter if you have any doubts. Have fun!