Why you don’t need them to finish the story—and why you’ll remember them if you go.
Story speedruns are fun—but Kanto shines when you wander off the main path. Gen I is packed with dungeons you can skip without getting stuck yet deliver peak “Pokémon vibes.” Below, each spot is framed on two axes: Why it’s not required and Why it’s worth the detour.
1) Diglett’s Cave (Vermilion ↔ Route 2)
Why not required: You’re “supposed” to grab HM05 Flash on Route 2 for Rock Tunnel, but you can clear Rock Tunnel without Flash by hugging the walls.
Why it’s worth it: High-level Dugtrio can appear—an instant answer to Lt. Surge thanks to STAB Ground moves and ridiculous Speed.
2) S.S. Anne (Vermilion City)
Why not required: The usual route is boarding to obtain HM01 Cut from the captain. However, if you trade in a Pokémon that already knows Cut, you can skip the ship entirely (a classic Gen I sequence break).
Why it’s worth it: Iconic luxury-liner setting, dense trainer EXP, and a memorable rival battle—pure early-game spectacle.
3) Team Rocket Hideout (Celadon Game Corner Basement)
Why not required: Normally you raid it for the Silph Scope to reveal Pokémon Tower’s ghost. But in Gen I you can use a Poké Doll on the ghost to bypass the fight and reach the top anyway—no Scope needed.
Why it’s worth it: Spinning-tile puzzles, swarms of Grunts, and that delicious “evil-lair under a casino” energy.
4) Seafoam Islands (Route 20)
Why not required: Many players traverse Fuchsia → Cinnabar through Seafoam, but you can simply surf south from Pallet Town (Route 21) to reach Cinnabar without touching the islands.
Why it’s worth it: Boulder-drop water-flow puzzle and a showdown with Articuno—Kanto’s coolest (literally) optional legend.
5) Power Plant (off Route 10)
Why not required: A pure side dungeon—no story keys or HM gates depend on it.
Why it’s worth it: Moody abandoned-facility atmosphere loaded with Magnemite/Voltorb, plus the mighty Zapdos waiting within.
6) Cerulean Cave (a.k.a. Unknown Dungeon)
Why not required: Post-League only. It opens after you become Champion, so it’s by definition optional.
Why it’s worth it: Peak-level wild encounters and the ultimate prize at the end: Lv. 70 Mewtwo—Kanto’s true final exam.
Closing Thought: Detours Define Kanto
You can hit the credits without any of these, but each detour adds texture—rare encounters, tactile puzzles, urban legends, and clever skips (hello, Poké Doll). Try a “beeline run” one day and an “all-detours tour” the next; same story, totally different feel. If you’re booting up Gen I again, start with this “optional map”—you’ll likely uncover something you missed the first time.
