I've released a 2D style mod for UT2004 which gives you a sidescrolling perspective and changes the gameplay to be more something like Soldat.
There are quite a few compatible maps and the gameplay is great fun, so please go take a look and download it.
You can get it from the official Marshmallow Duel : Mowbray's Revenge website, in the files section.
Unrelatedly, I'm going to take the comments section down later today because it isn't working very well and it totally annoys me. I will probably replace the comments link with a link to Mduel:MR soon, since that is where most of my work and released stuff will be going for probably the next year.