Crud...
Ok, the new engine is 1/2 way implemented, a hyper beta demo of it is up for download, it's engine180.gmd, at the first page d-load link.
[Edit]
...I got ninja'd. Crap...
You posted before I was done typing. And your post is long!!!
^ And in reply to the above post ^
I'm currently working on implementing Dami's slope engine for GM5.3 into the game. engine180.gmd is the ultra-beta...ish new demo. GM5 is needed. EXE will come soon.
[edit 2]
engine180.exe is up. That's the ultra-beta (almost alpha-ish) engine test.
Download page:
http://www.4shared.com/dir/2277153/c01b1c0/Fangames.html