Some targets supported by z88dk may be headless and the console is presented using a serial connection (either physical or bridged to network).
On these machines, you may still want to display graphics, well now you can with the z88dk libraries! - z88dk now provides monochrome graphic support for Tektronix 401x and ReGIS capable (VT125, VT240, VT340) terminals.
These displays are more suited to display graphs than games, but if you've implemented a collision algorithm that doesn't read the screen then it may well be possible to get something working.
Not all of the monochrome library is supported, but you can draw primitives (and on ReGIS terminals undraw them) and a putsprite() implementation could be written for ReGIS if wanted - just let me know and I'll see what I can do.
There's a wiki page with some more details here: https://github.com/z88dk/z88dk/wiki/Cla ... s-graphics