I think the 2 day period is a bit too short to properly do a run, maybe you could change it too a week? Oh and maybe do an impregnation mechanic, like as an added bonus for pleasing a mare while your bar is very unfilled and you play those orgasm cards it fills this bonus score and if you fill it you get something extra like more tension max per impreg. and lastly, more customization options for the player like going anthro or maybe being a dragon (or human), although the amount of work for this idea may be a bit too much considering all the card art that may be needed to do that.