That's usually called tactical gameplay & the fact that the dmg flanking/facing rules are so hostile to the mere existence makes it worse. I'd add "that bring subjective choices to equipment like past editions" & "that are balanced for the creation of a magic item budget & accompanying monster rework formulas" or similar to some of @Minigiant's list in #449 then toss in "a rework of phb197 & new recovery rules to strip wolverine/deadpool's mutant healing factor from the average pc". Sadly some of the dmg variant options show that wotc was at least at one point willing to create rules that check a box in name while seeming to deliberately avoid actually meeting the need to go with it.Most of the genre related options depend on the setting, and belong in a setting guide.
With regard to mechanical rules, the only "modular" option that I notice some players asking for is more chess-like options for grid and miniatures.
Am I misunderstanding the modes that people are asking for?
@Parmandur I feel like I've heard that somewhen before, perhaps 2009, maybe 2008. I'm sure it's mere coincidence