Spelunky is © 2008, 2009 Derek Yu and Mossmouth, LLC, and is used under the [Spelunky User License v1.1b](https://spelunky.ai/LICENSE.txt). spelunky.ai is an unofficial fan project, not affiliated with or endorsed by Mossmouth. The game and its assets may not be sold. Music by George Buzinkai and Jonathan Perry; sound effects made in SFXR. From Spelunky Classic 1.1, © 2008, 2009 Derek Yu and Mossmouth, LLC. # Mothership From the spelunky.ai wiki: . Verified against the spelunky.ai port [v0.1.10](https://github.com/851-labs/spelunky/releases/tag/v0.1.10) on 28 October 2026. The mothership is an alien craft in Spelunky Classic, on some Ice Caves levels after the Moai's, holding the Alien Boss behind a barrier and a free Jetpack. ![A grey metal emitter, a pink beam crackling from its base](https://spelunky.ai/wiki/media/583f7aa191eace98/sprites/sBarrierEmitter/anim%404x.png) | Mothership | | | ---------- | ------------------------------------------------------- | | Levels | 10–12[^1] | | Chance | 1 in 10 for each Ice Caves level after the Moai's[^2] | | Part of | [The Ice Caves](https://spelunky.ai/wiki/ice-caves)[^2] | The mothership lies across a row of rooms, from one of the level's first three columns to its right edge: a hull of grey metal plates over a metal floor, closed all round. In its last room, at the level's edge, sits the [Alien Boss](https://spelunky.ai/wiki/alien-boss), behind a crackling pink barrier, with a free [Jetpack](https://spelunky.ai/wiki/jetpack) beside it. The level starts with the message "THERE'S A PSYCHIC PRESENCE HERE!" The code calls it the alien craft[^3]. ## Generation On an [Ice Caves](https://spelunky.ai/wiki/ice-caves) level after the [Moai](https://spelunky.ai/wiki/moai)'s, the mothership comes one time in 10[^2][^4]. Its roll is the other branch of the Moai's, which every Ice Caves level takes until the Moai is made, so a level before the Moai's, or the Moai's own, never has it, and the mothership only comes on levels 10, 11 and 12[^5]. A level with it can't also be a [Yeti lair](https://spelunky.ai/wiki/yeti-lair), whose roll is only made when this one fails[^6]. It starts with "THERE'S A PSYCHIC PRESENCE HERE!"[^7][^8]. **Clip: Arriving over the mothership.** An Ice Caves level loads with the message "THERE'S A PSYCHIC PRESENCE HERE!" Under the player's ledge lies the alien craft, and in its last room the Alien Boss, behind a pink barrier. It sends a psychic wave up through the hull, which knocks the player down and takes a heart. ([video](https://spelunky.ai/wiki/media/583f7aa191eace98/clips/mothership/psychic-presence/clip.mp4)) In the clip, the mothership's level loads with its message. The craft lies under the player's ledge, and the Alien Boss, in its last room, sends a psychic wave up through the hull, which knocks the player down and takes a heart[^9]. Once the level's path is laid, the craft takes a row of rooms, the second or third, chosen at random, from a random room that isn't the last in the row to the right edge, whatever the path had put there. So it's two, three or four rooms long[^10]: | Room | What's in it | | | --------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----- | | The first | The craft's nose and front: its front plates, and blocks of ice that close it above them | [^11] | | Each between | Hull above, floor below, nothing between | [^12] | | The last, at the right edge | The [Alien Boss](https://spelunky.ai/wiki/alien-boss); the barrier's emitter in the hull in front of it; behind it, a free [Jetpack](https://spelunky.ai/wiki/jetpack) in a block of rock; rock along the room's right side | [^13] | The hull and the floor are blocks, which a bomb breaks as it does the rock, into dark rubble[^14][^15][^16]. Seven of the last room's ten floor blocks are each, one time in 2, a block of the area's rock or ice instead[^17]. The windows and the machinery inside are drawn behind, and stop nothing[^18]. ## Inhabitants | Monster | Where | Chance | | | ------------------------------------------------- | --------------------- | ----------------------- | ----- | | [Alien Boss](https://spelunky.ai/wiki/alien-boss) | The craft's last room | One in every mothership | [^19] | The Alien Boss doesn't move on its own, and sends psychic waves after a player who comes near, which pass through walls ([its page](https://spelunky.ai/wiki/alien-boss#behaviour) has how it fights). When it dies, the barrier comes down[^20]. Level generation goes over the craft's blocks as over the rock, so [the Ice Caves'](https://spelunky.ai/wiki/ice-caves#inhabitants) [Yetis](https://spelunky.ai/wiki/yeti) can stand on its floor and its hull, and [UFOs](https://spelunky.ai/wiki/ufo) hover over it[^21]. ## Hazards - **The barrier.** The emitter in the last room's hull makes one barrier, a beam three blocks tall down to the floor, between the front of the room and the Alien Boss[^22][^23]. A player who touches it loses a heart, and is thrown back away from it and made invincible for 30 steps (1 second)[^24]. Items that touch it are thrown back to the left, and out of the player's hands; a [Bomb](https://spelunky.ai/wiki/bomb) is lit, set to go off in 4 to 8 steps[^25]. Bullets and the [Web Cannon](https://spelunky.ai/wiki/web-cannon)'s webs stop at it[^26][^27]. - **Bringing the barrier down.** Destroying the emitter destroys the barrier[^28]. An explosion destroys it, as do a bullet and an item that hits it moving faster than 2 pixels a step[^29][^30][^31]. It also breaks once it's on screen with the block above it gone, and when the Alien Boss dies[^32][^20]. - **The Ice Caves' own**: the drop below the level, ice, and [Spring Traps](https://spelunky.ai/wiki/spring-trap) ([the Ice Caves' hazards](https://spelunky.ai/wiki/ice-caves#hazards)). ## Items and shops The Jetpack in the last room is free: it's made with no price and not for sale, set in a block of rock behind the Alien Boss[^33]. The Alien Boss leaves 4 big gems when it dies, each a [Big Emerald](https://spelunky.ai/wiki/big-emerald), a [Big Sapphire](https://spelunky.ai/wiki/big-sapphire) or a [Big Ruby](https://spelunky.ai/wiki/big-ruby)[^34]. The rest of the level is as [any Ice Caves level](https://spelunky.ai/wiki/ice-caves#items-and-shops): its shops, its treasure, and Kali's altar and the [Golden Idol](https://spelunky.ai/wiki/golden-idol)'s room in its side rooms. A shop only takes a room the path left empty, and the craft's rooms are its own by then, so a shop is never in the craft[^35]. ## Trivia - The craft's floor is made of hull blocks given the floor's sprite. There's an object of its own for the floor, `oAlienShipFloor`, but nothing makes one[^36][^5]. - The Yeti lair's roll checks that the level hasn't got the alien craft, which it can't have by then: that roll is only made when the craft's has failed[^37]. ## FAQ ### How do you find the mothership in Spelunky Classic? By chance: each [Ice Caves](https://spelunky.ai/wiki/ice-caves) level after the one with the [Moai](https://spelunky.ai/wiki/moai) has a 1 in 10 chance of holding it, so it can only be on levels 10 to 12. The level starts with the message "THERE'S A PSYCHIC PRESENCE HERE!" ### What is in the mothership in Spelunky Classic? The [Alien Boss](https://spelunky.ai/wiki/alien-boss), in the craft's last room behind a barrier, and beside it a free [Jetpack](https://spelunky.ai/wiki/jetpack), set in a block of rock. ### How do you get past the mothership's barrier in Spelunky Classic? By destroying the emitter in the ceiling that makes it: a bomb's explosion, a bullet, or an item thrown into it fast. Breaking the hull above the emitter, or killing the [Alien Boss](https://spelunky.ai/wiki/alien-boss), destroys it too. Touching the barrier costs a heart. ### Can the mothership and a Yeti lair be on the same level in Spelunky Classic? No. The [Yeti lair](https://spelunky.ai/wiki/yeti-lair)'s roll is only made when the mothership's fails, and neither can be on the [Moai](https://spelunky.ai/wiki/moai)'s level. ## See also - **Related:** [Moai](https://spelunky.ai/wiki/moai), [Yeti Lair](https://spelunky.ai/wiki/yeti-lair), [UFO](https://spelunky.ai/wiki/ufo) - **Found here:** [Alien Boss](https://spelunky.ai/wiki/alien-boss), [Jetpack](https://spelunky.ai/wiki/jetpack) ## References [^1]: [`scripts/scrLevelGen.gml:212-233`](https://spelunky.ai/wiki/source/scripts/scrLevelGen#L212-L233) [^2]: [`scripts/scrLevelGen.gml:222-233`](https://spelunky.ai/wiki/source/scripts/scrLevelGen#L222-L233) [^3]: [`scripts/scrLevelGen.gml:222`](https://spelunky.ai/wiki/source/scripts/scrLevelGen#L222) [^4]: [`scripts/scrClearGlobals.gml:59`](https://spelunky.ai/wiki/source/scripts/scrClearGlobals#L59) [^5]: Quirk 1 (docs/quirks.md) [^6]: [`scripts/scrLevelGen.gml:234-237`](https://spelunky.ai/wiki/source/scripts/scrLevelGen#L234-L237) [^7]: [`objects/oPlayer1/alarm_0.gml:46-51`](https://spelunky.ai/wiki/source/objects/oPlayer1/alarm_0#L46-L51) [^8]: [`scripts/scrInitLevel.gml:206-220`](https://spelunky.ai/wiki/source/scripts/scrInitLevel#L206-L220) [^9]: Clip mothership/psychic-presence [^10]: [`scripts/scrLevelGen.gml:224-231`](https://spelunky.ai/wiki/source/scripts/scrLevelGen#L224-L231) [^11]: [`scripts/scrRoomGen3.gml:161-167`](https://spelunky.ai/wiki/source/scripts/scrRoomGen3#L161-L167) [^12]: [`scripts/scrRoomGen3.gml:168-174`](https://spelunky.ai/wiki/source/scripts/scrRoomGen3#L168-L174) [^13]: [`scripts/scrRoomGen3.gml:175-181`](https://spelunky.ai/wiki/source/scripts/scrRoomGen3#L175-L181) [^14]: [`scripts/scrRoomGen3.gml:408-418`](https://spelunky.ai/wiki/source/scripts/scrRoomGen3#L408-L418) [^15]: [`objects/oAlienShip/destroy.gml:1-5`](https://spelunky.ai/wiki/source/objects/oAlienShip/destroy#L1-L5) [^16]: [`objects/oExplosion/collision_oSolid.gml:1-15`](https://spelunky.ai/wiki/source/objects/oExplosion/collision_oSolid#L1-L15) [^17]: [`scripts/scrRoomGen3.gml:419-432`](https://spelunky.ai/wiki/source/scripts/scrRoomGen3#L419-L432) [^18]: [`scripts/scrRoomGen3.gml:451-460`](https://spelunky.ai/wiki/source/scripts/scrRoomGen3#L451-L460) [^19]: [`scripts/scrRoomGen3.gml:461-464`](https://spelunky.ai/wiki/source/scripts/scrRoomGen3#L461-L464) [^20]: [`objects/oAlienBoss/other_animation_end.gml:1-5`](https://spelunky.ai/wiki/source/objects/oAlienBoss/other_animation_end#L1-L5) [^21]: [`scripts/scrEntityGen.gml:338-379`](https://spelunky.ai/wiki/source/scripts/scrEntityGen#L338-L379) [^22]: [`scripts/scrRoomGen3.gml:479-482`](https://spelunky.ai/wiki/source/scripts/scrRoomGen3#L479-L482) [^23]: [`objects/oBarrierEmitter/create.gml:1-5`](https://spelunky.ai/wiki/source/objects/oBarrierEmitter/create#L1-L5) [^24]: [`objects/oBarrier/collision_oCharacter.gml:1-13`](https://spelunky.ai/wiki/source/objects/oBarrier/collision_oCharacter#L1-L13) [^25]: [`objects/oBarrier/collision_oItem.gml:1-17`](https://spelunky.ai/wiki/source/objects/oBarrier/collision_oItem#L1-L17) [^26]: [`objects/oBarrier/collision_oBullet.gml:1-6`](https://spelunky.ai/wiki/source/objects/oBarrier/collision_oBullet#L1-L6) [^27]: [`objects/oBarrier/collision_oWebBall.gml:1-4`](https://spelunky.ai/wiki/source/objects/oBarrier/collision_oWebBall#L1-L4) [^28]: [`objects/oBarrierEmitter/destroy.gml:1-11`](https://spelunky.ai/wiki/source/objects/oBarrierEmitter/destroy#L1-L11) [^29]: [`objects/oExplosion/collision_oBarrierEmitter.gml:1`](https://spelunky.ai/wiki/source/objects/oExplosion/collision_oBarrierEmitter#L1) [^30]: [`objects/oBarrierEmitter/collision_oBullet.gml:1`](https://spelunky.ai/wiki/source/objects/oBarrierEmitter/collision_oBullet#L1) [^31]: [`objects/oBarrierEmitter/collision_oItem.gml:1-4`](https://spelunky.ai/wiki/source/objects/oBarrierEmitter/collision_oItem#L1-L4) [^32]: [`objects/oBarrierEmitter/step.gml:1-5`](https://spelunky.ai/wiki/source/objects/oBarrierEmitter/step#L1-L5) [^33]: [`scripts/scrRoomGen3.gml:472-478`](https://spelunky.ai/wiki/source/scripts/scrRoomGen3#L472-L478) [^34]: [`objects/oAlienBoss/step.gml:9-25`](https://spelunky.ai/wiki/source/objects/oAlienBoss/step#L9-L25) [^35]: [`scripts/scrLevelGen.gml:239-297`](https://spelunky.ai/wiki/source/scripts/scrLevelGen#L239-L297) [^36]: [`scripts/scrRoomGen3.gml:413-418`](https://spelunky.ai/wiki/source/scripts/scrRoomGen3#L413-L418) [^37]: [`scripts/scrLevelGen.gml:222-237`](https://spelunky.ai/wiki/source/scripts/scrLevelGen#L222-L237) ### Source code - [`scripts/scrLevelGen.gml`](https://spelunky.ai/wiki/source/scripts/scrLevelGen) - [`scripts/scrRoomGen3.gml`](https://spelunky.ai/wiki/source/scripts/scrRoomGen3) - [`objects/oBarrierEmitter/create.gml`](https://spelunky.ai/wiki/source/objects/oBarrierEmitter/create) - [`objects/oBarrierEmitter/step.gml`](https://spelunky.ai/wiki/source/objects/oBarrierEmitter/step) - [`objects/oBarrier/collision_oCharacter.gml`](https://spelunky.ai/wiki/source/objects/oBarrier/collision_oCharacter) - [`objects/oBarrier/collision_oItem.gml`](https://spelunky.ai/wiki/source/objects/oBarrier/collision_oItem)