Hey Muhznit, did you happen to play the short game I made a couple weeks ago?
http://tfgamessite.com/?module=viewgame&id=954
I've been pondering the issues of TF game design for a while, now. In fact, I've been meaning to write a dA journal about all the issues you mention: mainly how most games have players actively avoiding the transformation content they're here to see, or striving to lose in as many ways possible.
Check out Bimbo Sequencer 1.0 above, or the GROW games that inspired it:
http://www.eyezmaze.com/eyezblog_en/...nano_vol3.html
I feel it's a mechanic that "fits" TF games like a glove. You're trying to optimize for the "perfect" bimbo (or catgirl, or succubus, or whatever) but there's an element of experimentation and problem solving which makes the process very engaging. Unlocking a new "tier" is super rewarding and even failure doesn't feel bad because it's part of figuring things out and still results in
some content. You can actually make surprisingly complex games by increasing the sequence length. Honestly, it's such a perfect, obvious match that I'm surprised it hasn't been done before.
Obviously, the art assets required are substantial, but that's true of any good TF game. The only other drawback I can think of is the relatively low replay value. At the end of the day, though, it's intended to be fap material. I'd say keeping the player engaged for 15-30 minutes is more than enough.