Continuing with the 8 bit fascination, the Sierra game engine from those days was quite impressive.  It had static bitmaps for rooms, collision objects, Z buffering, & player animation.  It used vector graphics.

Young lion envisioned some mix of scrolling world & static rooms for his Robotech game.  A scrolling world would have been quite unplayable, in the end.  Truth be known, the signature graphical Sierra adventure games never supported the C64.  They were all on x86 & apple II, using plain bitmap writes.  Kiwipedia clearly shows the C64 wasn't supported.  https://en.wikipedia.org/wiki/Adventure_Game_Interpreter

Their most advanced games for C64 just had non interactive, procedurally drawn graphics as illustrations.   Their most advanced C64 adventure game was Mickey's Space Adventure.

They made a formal game engine for x86 & apple II starting with King's quest.  It had a very small player & very few occluded zones.  The mane mystery is why they didn't do the same on the C64.

They all drew the graphics in place.  Very few of the current generation has any memory of watching a flood fill algorithm slowly fill an area.  It was a 160x150 graphical area with a 30 pixel tall text area below.  It seems to have dropped 20 pixels from the top & bottom.

This room is using an alpha mask to draw the chain on top of the player.  A C64 would have to use sprites for the foreground or just draw the whole thing in bitmap RAM.

As usual, the hardest part would be creating the assets & plot.