Alto in 1-4

Dwelling

Golden Key and Chest on 1-2 through 1-3
Ghist Store in 1-4 if cursed below the boss

Left Exit
Right Exit

Shortcut unlocked with $2000, 1x Bomb and $10,000.

Liz in random stage
Nekka in Black Market

Jungle

Rescue Three Sisters for items at Olmec
Obtain Hedjet from Black Market
Complete Moon Trial for Hou Yi's Bow

LISE in random stage
Coco in Vlad's Keep

Volcana

Rescue Van Horsing
Use Eye on Drill and obtain Crown from Vlad's Keep
Complete Moon Trial for Hou Yi's Bow

Shortcut unlocked with 1x Rope, A Weapon and A Mount.

Olmec's Lair

Manfred in Ankh chamber

Defeat Olmec for Ankh.
Give Bow to Waddler for safekeeping.

Second Layer
First Layer

Temple of Anubis

Valerie in random stage
Au in City of Gold

Defeat Anubis in 4-1 and obtain Scepter
Enter City of Gold and die on Golden Altar

Jay in random stage

Tide Pool

Obtain Excalibur in 4-2
Trigger Lava Trap in 4-3

Duat

Defeat Osiris and obtain Tablet of Destiny

Tina

Abzu

Defeat Kingu and obtain Tablet of Destiny

Shortcut unlocked with $50,000, A Hired Hand (Abzu recommended as source) and the Golden Key from the Dwelling.

Ice Caves

Demi in Yeti Cave
Pilot in Mothership

Eggplant can be placed on altar for Eggplant Child
Mothership is hidden in the background layer

Neo Babylon

Airyn in random stage

Enter Ushabti Room on 6-2 and find correct one with Tablet of Destiny
Qilin hatches on 6-3

Tiamat's Throne

Guy Spelunky for boss clear

Standard Ending
Defeat or skip Tiamat and ride Qilin to top of area

Sunken City

Dirk in random stage

Eggplant Child on Mother Status for Eggplant City
Collect the Hou Yi's Bow and complete Sun Trial for Sun Arrow

Hundun's Hideaway

Classic Guy for boss clear

Good Ending
Defeat Hundun and shoot his Eye with the Sun Arrow

Cosmic Ocean

99 Stages, become a constellation based on your run's actions