The video you've posted above, about the tile making plugin for Unity, inspired me to give it a try, so today (beside of my main project) I've started something very small, but maybe useful! Tile making (editor?), that reads the level from the .txt file and in near future, will save it back to it (.txt file). This is what I've done for couple of hours:

I've made only some basic stuff at the moment (camera movement etc), those tiles in the screen above are placed run-time from the map01.txt file. For now, it supports three different object types, background, wall and light, but it's really easy to add new objects. If I could make this save back to .txt file, it would be great! I'm thinking how to make that one atm.. or maybe, I'll read and save level from the image file (as I'm waiting for Helghast to reply my question). If this will come to the end, I could share it with you, if you need it. It's a side scroller oriented now (2D), but could be easily redone for top down 2D tile system.