I put an executable in the zone (TKG_doublewidth.zip)
This one is compiled to render properly in doublewidth (2x1,2x2) modes, switchable via left bracket on numpad. It has issues with music and the load/save menu on a real machine.
I also merged a couple of commits back into master. The DOUBLEWIDTH_test branch now has one commit dedicated to all the places that need either a "multiply by two" or "divide by two" to achieve the doublewidth rendering.
Now it would be interesting to figure out how to roll these multipliers into few "higher up" places and thus unify 1x and 2x modes. Maybe someone has ideas to join in?
A similar effort will have to be done for double-height rendering.
There's also an interesting issue with the floor still "swimming" a bit wrt to the walls. I think this is due to me extending the render area from 288x232 to 320x232 in fullscreen. Walls and floor use slightly different formula to express the field of view. I think this peculiar code here
https://github.com/mheyer32/alienbre.../hires.s#L9550
is doing that for the floor (the multiplication of 0.75 in there). It would be good to somehow consolidate this, too.
So much to do, so little time :-(