Board Thread:General Discussion/@comment-26006155-20190820122909/@comment-26907577-20190826111741

You've misread yet again. The proposal being made is that Gaster brought modern technology when he came to the Underground in 1700s AD which is a few years before Asriel was born.

Timeline:
 * 1) War of Humans and Monsters in medieval time
 * 2) Several years pass
 * 3) Monsterkind expands to the rest of the Underground.
 * 4) Gaster shows up, builds CORE
 * 5) Asriel is born
 * 6) About 10 years
 * 7) 201X
 * 8) Chara falls
 * 9) Gaster is shattered.
 * 10) Buttercup incident
 * 11) Many, many years, during which monster technology in the CORE is stagnant at Gaster's level and slowly increases in ability in the rest of the Underground. Six humans fall.
 * 12) Modern times. CORE is still futuristic, most of the Underground is modern.
 * 13) Frisk falls.