Since Steam has been introducing user tags several days(?) ago ( http://store.steampowered.com/tag/ ) it is possible to 'group' games by users. There is already a popular tag 'Visual Novel': http://store.steampowered.com/tag/en/Visual%20Novel/
However, while most other game engines do also have their own (well used) tags, Ren'Py doesn't…
http://store.steampowered.com/tag/en/Ren'py/ => Not enough tags to be visible currently!
I would like to encourage some of you to use it - and tag some of the Ren'Py-games on Steam with "Ren'Py" … As is is with tags: Every Ren'Py game will benefit from such kind of grouping!
(Note: It seems that the tag will look like "Ren'py" in the end - Steam seems to auto-correct it.)