1.7.2 works, but the game doesn't really hide the fact most of the models are mid-tier ports of SFM models that were ports of ports, so IDK if the download was really worth it. The Google Drive link was successful for me, but the site splits up the downloads weirdly and you have to extract all four manually to the same location.
"Kumflation" isn't very good on the few characters with support for it, and honestly it doesn't really work that great most of the time for the sole fact that you can't see their belly that well from most of the sex positions. Some games get around this by adding in a mirror or two into the room that you can look over at for other camera angles, but nope, nothing here, I think.
Still probably an okayish animation viewer for anyone who's a fan of r34, I guess.
Biggest downside is there's really no player interaction, you pick a pose and just let it go.