I started a windows playthrough, but that didn't go far.

For anyone curious about the platform and release date being off, I bought it on the Amazon Appstore, which did release on this day as intended, to play on Android.

Free Play Weekend on Steam. This session has the entire time according to Steam.

Free Play Weekend on Steam.

I actually don't know the date I played this on rn.

This final session was the only PS5 session. It is still marked as "Played on PS4" since I don't think there's a noticeable performance difference between the consoles for Undertale specifically. If I ever decided to play again, it will be marked as "Played on PS5"

This is a guess as I forgot when I started playing on PS5.

*Remaining collectibles. This site doesn't let you name logs beyond a certain amount of characters so I have this here.

I don't remember, but I can safely say I finished it before the year ended.

Start and Finish because I have a separate log for the rest of my playthrough

It took too long for me to figure out when I started this game.