This topic is a mission to uncover unknown unknowns in the game genre space.
Probably? primarily research oriented, this could be executed in two phases: 1) mapping systems in the world, 2) comparing this map to games that are made.
For the purposes of argument, we could call a system underrepresented if it does not have a ‘hit’ game made from it (say a game found on major indeces, such as metacritic or boardgamegeek, with above 4/5 stars in rating).
The intent of this would be to provide inspiration for future areas of game development, and possibly to theorize as to why certain systems become heavily represented and others not at all. A converse of this topic would be to chart which systems have very heavy representation as a comparative analysis to finding the “blank spots” on the map.
A sub point of the first objective (mapping systems in the world) would be to create a hierarchy of world systems to organize systems into larger groups. This would allow further granularity in measuring underrepresented genres if, for instance, bees are underrepresented but insects broadly are not, or insects are broadly underrepresented but animal systems are not.
A variation on the world system map would be to categorize systems by the emotions that they evoke, and establish a genre lens based on emotion — but this is probably too large to be a subtopic.