About a year or two ago, I began working on a co-op wad that I was not too happy with. At one point, I got the brainy idea of modifying MAP01 from my wad and turning it into a Death Match version, with revamped architecture and improved flow. The rest of the wad wasn't that great, and I didn't really think any of my other maps would go well with this -- so we have the final incarnation of MAP01, from my old co-op wad, in DM format!
New from scratch
My DM version took probably about a day. Based on my old Co-Op version of MAP01.