Menuless tweaking:
It's worth a shot to implement menuless tweaking. That's uncharted waters. You can be the first to find and nail good UI for it.
I encourage you to mark the previous skill assignment (or even the next?) directly on the main level view. I remember those "block here", "dig here" arrows from vanilla L3D tutorials. If we press a hotkey and see those markings change, we'll have nice feedback from the otherwise abstract replay editing functionality.
With the block-based physics, assignments are often delayed, e.g., assigned digger first walks until he reaches a block centerpoint. I'm envisioning the assignment markers to improve the feedback here, too, i.e., have better feedback directly after the assignment, before the lemming starts its new activity. That sounds helpful even if we never tweak a single assignment.
Menu-based tweaking:
You already have a minimap that you can hide and show with the small red corner button. You can implement the tweaker similarly, hidden by default, and shown on button click instead of the map, or instead of the right-side buttons. It needs a smaller font than the skill numbers.
Markers for most recent skill, or for upcoming skills, are handy even with a menu-based tweaker. There are lots of improvement ideas here across games (NL, Lix, Loap). E.g., if there is an exploder assignment scheduled within 5 seconds, Lix should show the countdown/fuse ahead of time. And why not something similar for other future skills?
-- Simon
