As of r25037, the hires mode is all gone, and the AGI engine is a thousand lines lighter.
--dsymonds 17:59, 6 January 2007 (UTC)
Sarien's hires mode causes some behavioural glitches, and should be removed in favour of leaving these Scale2x-style graphical enhancements to the ScummVM backends, especially since it can be made optional at that point.
The primary problem comes from AGI's priority screens, which control how the background scenery and the movable objects interact. For the uninitiated, you can think of it as a sort of "depth channel" (by analogy with an alpha channel). To add more complexity, control lines are also drawn on the priority screen, and they are responsible for the demarcation of no-go areas and for triggering various events (opening automatic doors, triggering traps, etc.).
AGI is a fairly touchy engine, and really requires pixel-perfect rendering internally; the hires mode thus causes a few problems, because it effectively smears the sharp borders that the rest of the AGI engine expects, leading to incorrect interpretation.
At the very least, this is redundant code, since the ScummVM backends can do the Scale2x effects, and have it configurable too!
Space Quest 2
These aren't actually errors, but give a feel for what could go wrong in other places.
Below is the priority screen for that room. Different colors are different depths: the ego can walk "between" the aqua bushes on the left and the green bushes on the right, but only when he's at the right "priority".
In fact, a bit further in to the game: (notice the diagonal control lines)