The first thing I did was count the unlockable scenes. 14 total, but two are just variations of Nami's handjob with different dialogue flags. That's the kind of thing I track. One Slice of Lust is a browser game, so no install, just click and the Straw Hats are suddenly horny because Blackbeard did something vague. The plot is thin, but you're not here for plot.
The massage minigame with Boa Sandersonia is where the game actually tries. You rub her shoulders, a meter fills, and if you hit the right spots she starts breathing heavier. The animation is simple 2D, but the way her chest moves during the titjob scene is... effective. I replayed that route three times to see if the cum on face ending was tied to a specific massage order. It is. Left shoulder, right shoulder, then neck. If you do neck first, you get the handjob instead. I wrote that down.
The sound is weird. There's no voice acting, just a looping ocean wave track that cuts off abruptly when a scene starts. It's like the audio file forgot to fade out. I wish they'd fixed that, but they won't. The Nami teasing scene has this little giggle sound effect that plays twice, and the second time it's slightly out of sync. Drove me crazy.
Robin's masturbation scene is the longest, but it's mostly static images with a slow pan. You can click to speed it up, which I did. The cum on face ending for her is locked behind a dialogue choice where you have to pick "I trust you" instead of "Show me". That's not explained anywhere. I found it by accident.
The game doesn't have a gallery, so if you miss a flag, you replay the whole chapter. I don't know why they did that. Maybe to pad the runtime. The titjob with Nami is worth it though. Her tits are drawn slightly too big for her body, but the bounce physics are consistent. I counted 12 frames of animation. That's more than the Robin scene.
One thing I noticed: the "fleet flora" tag is misspelled. It's supposed to be "fleet admiral" or something. The game has a typo in the tag list. That's the level of polish we're dealing with. But the handjob scene with Boa Sandersonia has this moment where she looks directly at the camera, and I felt something. Not love. Just... recognition. Like the game knew I was tracking its routes.