More info about each DF entry for those who don't know, more or less in release order:

• Uppertale: This game isn't actually DF, but it's about Frisk using Alphys's time machine to go back to Undertale after monsters were freed.

• DF Old Beta: This first version of DF, which started as an Uppertale remake, follows Frisk and Sans as they go to the Void (aka Lost World 3) to bring Gaster back into existence.

• DF Demo 2: This is a completely different story where Frisk finds Gaster's secret lab in an Undertale run and goes on a quest across timelines to collect his soul pieces. The demo only contains the Uppertale timeline, but the full game would've included the Void from the old beta as well.

• DF Story Mode (Chapter 1): This game introduces Harlow and the first chapter has them break out of the simulation by collecting Gaster's soul pieces. This chapter was also the only one released.

• DF Story Mode (Redux): A rewrite of the previous story that was never finished. Alongside introducing Frisk as a major character, this version would've put more emphasis on the fact that it's technically an Undertale prequel as Harlow gives up their SOUL to reset the timeline.

• Master Quest: This was the main quest line of DFC until v2.5.0 and involved the player searching for keys to unlock doors to different worlds in order to find out why everyone in the Underground went missing. Only the first three worlds were implemented, and they later became the Lost Worlds.

• DFC v2.8.0: While the current version of DFC doesn't have any lore, v2.8.0 will introduce a temporary story that RickyG has described as a "simplified, non-canon version" of DFC's canon story.

• DF Online Mode: DF v3.0.0, no longer subtitled "CONNECTED", will introduce the aforementioned "canon story", which will be implemented in multiple updates serving as chapters. Ricky has called this a "parallel narrative that explores an alternate timeline" to the also upcoming DF Story Mode.

• DF Story Mode: This is a Deltarune fangame with 4 planned chapters that are the length of DR Chapter 1, where we play as Harlow's "guardian angel" as they "become entangled in the aftermath of a tale from long ago"...

CREDITS

Custom old beta Gaster sprite by @RedmanGame