Things could've worked better if I'd either had the whole week off and
could've done this thing full-time, or if I'd already had an existing
code base for the missing systems which I could modify, instead of doing
things from scratch.
I clocked in 11 hours of focused work in my org-mode project tracker for
this, which isn't terribly much. Work was done on top of code from
miscellaneous Factor stuff I've done in the last 5 months, which
provides a reasonable basis for drawing nice sprites, but not that many
other handy game-building tools yet.