Been working for a while on a HORSES generator (random stats, based on real-world research). It's really a new system for horses, with an accompanying manual. Think: an advanced set of rules for mounts in D&D or other fantasy games.
It would unnecessarily slow down game play for the average game. But could be useful or fun in a horse-centric game or campaign, like a setting in Rohan, or the old West, or Dothraki. Could be a useful GM tool when the players want to hire a full-on wagon train to haul loot from the conquered tombs, but find there are only three old nags for sale in the nearby hamlet. And, as a player, I don't want my newly wealthy (400gp!) 2nd level rouge to purchase "Horse, riding, 25gp". I'd rather go to a large town, and select from:
Well, the generator is pretty well done, but the manual still has quite a ways to go to explain what all the stats mean.