Here is the full list of all 16 Oppaidius Tropical Cruise achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
You saw the Angela without panties secret scene!
You unlocked every art in the game! Now check the gallery, a surprise could await you there…
You remembered about that time, with the seagull…
You saw all the tic tac toe boxes’ scenes!
You achieved Angela’s max level affection points!
It’s the first time I’ve seen her smile…
You saw the VERY SCARY devs’ ghosts!
You chose the wrong “shortcut”…
5 minutes in a row looking at the cleavage rubbing scene… will it be enough…? (Of course it is not)
You achieved Rika’s max level affection points!
You surely are somebody’s type-you just need to hang in there!
You heroically resisted until the end…
Look at those melons!
Right, that’s the kind of “achievement” I didn’t need…
You began the adventure!
You set the “boobage level” to 100!