Wow, that's impressive use of graphics configuration tricks!
BTW: The second one only works really well with the following little bug fixed in "graphicsinfo.conf": Replace "global.forced_scroll_delay_value" with "game.forced_scroll_delay_value".
Is this a modified version of RnD that contains these enhancements? Where can it be downloaded from please?
The water breathing looks good, makes me thing of Cave Chaos 4 - or 3, or 2 - whichever one introduced the idea of water, anyway. The way water worked in that game was that when you touched a certain element water rose from nowhere to the level of that element, and you needed oxygen to survive when you went underwater.
The Cave Chaos series of games was/is such a great Boulderdash-type game; but I should save all my ravings on that for another post.
Regarding the separate playfields for both players, I find that idea confusing. The screenshot appears to show two separate caves (metal wall almost completely around the 'playfield', or maybe one cave with a row of blue pipe connecting the two areas. But I assume that separate playfields could work in any level, not one that needs to be designed to be a certain way?
How would separate playfields work with 3 players, or 4 players? Would one or both sides split horizontally as well, so there are up to 4 playfields?
Would the setting about how many tiles are needed before the playfield scrolls need to be handled differently?
And yeah, sorry for not mentioning that these are just made for testing some tricks with R'n'D's customization and so they can look very glitchy (especially the tape being totally covered by the game playfield and panel being black blank while the doors are opening and closing) and also the water is not animated because it's just a placeholder texture and should be changed