foreplaying, the less penetrating, the better.
Let's make a petition to DLsite (and ULMF?) so they create the "second base" and "third base" tags.
Your request is actually quite uncommon.
I can think about
https://ulmf.org/threads/rr-lost-fragments-rj247418.12846/ these guys focus mostly on non-penetrative content.
All games from 開発室
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heavily focus on foreplay; they tend to have difficult but interesting gameplay mechanics.
Perhaps exclude
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since all action is text-based (but a few boss scenes), with barely any nudity.
Foreplay is often favored in Lust Grimm
https://ulmf.org/threads/muni-munichi-studio-lust-grimm-rj198900.10457/
If you're looking for more, that niche is often the domain of shota MCs and Femdom (female domination) game... Don't ask me why, because I wish I knew. You could also try to search a specific fetish (Paizuri, armpit, hairjob, sumata, tickle, hand holding, etc.)
You probably know excessm already:
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https://ulmf.org/threads/24pe_ji-noekusupurooraa-3-rj222322.12276/ Sadly, the monster girls haven't aged much in 3 episodes: loli warning.