i have seen a few discutions in this forum about breast expansion in games, and there are a little bit hard to find, so... i will post a few titles that i have found, and whenever i found one worth telling i will posst about it:
hypnosis- great game
dungeon slaves- great game
nanpa beach- when the girl get pregnant, they get bigger...even bigger
peasant quest - also they get bigger while pregnant, lot of content and an incredible game overall
apocalypse- great game and dev is very active in forums
a new dawn
a goblins tale- one girl get a little bit bigger...so far
my new neighbors-corruption and most of the girls get bigger, great game
contamination- also contain futa
mythic manor- one girl can steal boobs
the pill- short-fun - very BE oriented
monikersmiths bloodlines- they transform in busty vampires
deviant discoveries - corruption and slutification
those are a few a remember, i will keep this updated as i find more