Alien Missions in Enemy Unknown (OpenXcom) - Revision history

Hobbes: Undo revision 126419 by Hobbes (talk)

2026-03-10T14:48:49Z

Undo revision 126419 by Hobbes (talk)

Hobbes: Removed protection from "Alien Missions in Enemy Unknown (OpenXcom)"

2026-03-10T14:47:50Z

Removed protection from "Alien Missions in Enemy Unknown (OpenXcom)"

← Older revision	Revision as of 14:47, 10 March 2026
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Hobbes: Protected "Alien Missions in Enemy Unknown (OpenXcom)" ([Edit=Allow only administrators] (indefinite) [Move=Allow only administrators] (indefinite))

2026-03-10T13:58:12Z

Protected "Alien Missions in Enemy Unknown (OpenXcom)" ([Edit=Allow only administrators] (indefinite) [Move=Allow only administrators] (indefinite))

← Older revision	Revision as of 13:58, 10 March 2026
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Hobbes: Redirected page to OpenXcom

2026-03-10T13:57:30Z

Redirected page to OpenXcom

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Hobbes: /* Alien Missions Generation */

2018-07-11T11:14:21Z

Alien Missions Generation

← Older revision		Revision as of 11:14, 11 July 2018
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	The aliens will generate new missions each month according to the following pattern:		The aliens will generate new missions each month according to the following pattern:
	* January, 1999: 1 Alien Research on the region of the initial XCom base, 1 Alien Terror		* January, 1999: 1 Alien Research on the region of the initial XCom base, 1 Alien Terror
	* February to ~~May~~, 1999: 1 random mission, 1 Alien Terror		* February to June, 1999: 1 random mission, 1 Alien Terror
	* ~~June~~, 1999: 2 random missions, 1 Alien Terror		* July, 1999: 2 random missions, 1 Alien Terror
	* Once an Infiltration mission starts on a region it will repeat itself indefinitely on that region, and it will keep spawning bases after all countries have signed pacts with the aliens		* Once an Infiltration mission starts on a region it will repeat itself indefinitely on that region, and it will keep spawning bases after all countries have signed pacts with the aliens
	* Starting on the first month, each shootdown of a UFO can trigger a retaliation mission by the aliens, with the chance being determined by difficulty level, at Easy being 4%, then increasing each difficulty level by 4%, until it reaches 20% on Superhuman		* Starting on the first month, each shootdown of a UFO can trigger a retaliation mission by the aliens, with the chance being determined by difficulty level, at Easy being 4%, then increasing each difficulty level by 4%, until it reaches 20% on Superhuman

Hobbes: /* Mission Zones */

2017-08-20T12:07:48Z

Mission Zones

← Older revision		Revision as of 12:07, 20 August 2017
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	* MissionZone 1 & 2 - used for landings on several missions		* MissionZone 1 & 2 - used for landings on several missions
	* MissionZone 3 - cities that appear on Geoscape and they are used by Alien Infiltration and Alien Terror missions for landings		* MissionZone 3 - cities that appear on Geoscape and they are used by Alien Infiltration and Alien Terror missions for landings
	* MissionZone 4 - Used for landings of UFOs on Infiltration and Base missions		* MissionZone 4 - Used for landings of UFOs on Infiltration and Base missions. Also used as the locations to spawn bases
	* MissionZone 5 - used exclusively as UFO spawn/despawn areas before heading towards the regions where the mission will take place		* MissionZone 5 - used exclusively as UFO spawn/despawn areas before heading towards the regions where the mission will take place. These zones are usually located in a different world region

	As an example, this image displays the Mission Zones for Europe.		As an example, this image displays the Mission Zones for Europe.

Hobbes: more edits

2016-08-18T16:16:03Z

more edits

← Older revision		Revision as of 16:16, 18 August 2016
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	'''Additional Info'''		'''Additional Info'''
	* The actual value of the timer between missions will be set between 50-150% of the value above displayed above.		* The actual value of the timer between missions will be set between 50-150% of the value above displayed above.
	* Shooting down a UFO will add 8-9 days (~~12000~~ - 13340 min) to the next timer~~. The formula is: 30 * (RNG::generate(0, 48) + 400)~~		* Shooting down a UFO will add 1-9 days (1440 - 13340 min) to the next timer
	*Those delays from shooting down UFOs can postpone Alien missions to the next month, which can result in situations such as 2 Terror Sites in the same month.		* Those delays from shooting down UFOs can postpone Alien missions to the next month, which can result in situations such as 2 Terror Sites in the same month

	===UFO Trajectories===		===UFO Trajectories===
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	===Mission Zones===		===Mission Zones===
	Finally, each region can have up to 6 types of Mission Zones, defined under [[Ruleset Reference (OpenXcom)#Regions\|Regions]], corresponding to different areas on the map. ~~Mission Zones 5 are used exclusively~~ as ~~UFO entry/exit~~ areas ~~from the globe, while the others can be~~ used ~~either~~ for ~~travel or~~ landings~~, depending~~ on ~~the UFO's trajectory and mission. Mission Zones~~ 3 ~~are the~~ cities that appear on Geoscape and they are used by Alien Infiltration and Alien Terror missions for landings.		Finally, each region can have up to 6 types of Mission Zones, defined under [[Ruleset Reference (OpenXcom)#Regions\|Regions]], corresponding to different areas on the map. Each type serves as a specific role:
			* MissionZone 0 - areas used for UFOs when arriving at a specific region. Also regularly used by UFOs to transit between other missionZones. UFOs never land on this missionZone
			* MissionZone 1 & 2 - used for landings on several missions
			* MissionZone 3 - cities that appear on Geoscape and they are used by Alien Infiltration and Alien Terror missions for landings
			* MissionZone 4 - Used for landings of UFOs on Infiltration and Base missions
			* MissionZone 5 - used exclusively as UFO spawn/despawn areas before heading towards the regions where the mission will take place

	As an example, this image displays the Mission Zones for Europe.		As an example, this image displays the Mission Zones for Europe.

Hobbes: /* Mission Frequency */

2016-08-18T15:39:39Z

Mission Frequency

← Older revision		Revision as of 15:39, 18 August 2016
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	** There can only be 1 active Retaliation mission per region		** There can only be 1 active Retaliation mission per region
	* After [[The Martian Solution]] is researched OR depending the difficulty level (March 2000 on Easy or November 1999 on Superhuman): 1 Alien Retaliation mission is added, in addition to the above		* After [[The Martian Solution]] is researched OR depending the difficulty level (March 2000 on Easy or November 1999 on Superhuman): 1 Alien Retaliation mission is added, in addition to the above
	** The detection chance for Retaliation missions is given by the formula: (completedFacilities / 6 + 15) / (mindShields + 1)~~. Hangars count as 1 completedFacilities, not as 4~~		** The detection chance for Retaliation missions is given by the formula: (completedFacilities / 6 + 15) / (mindShields + 1)
	* There is a 6% chance for a supply mission to be generated each day, for each alien base		* There is a 6% chance for a supply mission to be generated each day, for each alien base

Hobbes: /* UFO waves */ corrections

2016-08-18T15:36:02Z

UFO waves: corrections

← Older revision		Revision as of 15:36, 18 August 2016
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	\|}		\|}

	The actual value of the timer between missions will be set between 50-150% of the value above displayed above. Shooting down a UFO will add 1-9 days (~~1440~~ - ~~12960~~ min.) to the next timer. ~~For more details check the [[MISSIONS.DAT]] page. {{Template~~:~~Verify}}~~		'''Additional Info'''
			* The actual value of the timer between missions will be set between 50-150% of the value above displayed above.
	Those delays from shooting down UFOs can postpone Alien missions to the next month, which can result in situations such as 2 Terror Sites in the same month.		* Shooting down a UFO will add 8-9 days (12000 - 13340 min) to the next timer. The formula is: 30 * (RNG::generate(0, 48) + 400)
			*Those delays from shooting down UFOs can postpone Alien missions to the next month, which can result in situations such as 2 Terror Sites in the same month.

	===UFO Trajectories===		===UFO Trajectories===

Hobbes: /* Mission Frequency */ more details

2016-08-18T15:26:25Z

Mission Frequency: more details

← Older revision		Revision as of 15:26, 18 August 2016
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	===Mission Frequency===		===Mission Frequency===
	The aliens will generate new missions each month according to the following pattern:		The aliens will generate new missions each month according to the following pattern:
	* January, 1999: 1 Alien Research on the region of the initial XCom base, 1 Alien Terror~~, shooting down UFOs may trigger an Alien Retaliation mission~~		* January, 1999: 1 Alien Research on the region of the initial XCom base, 1 Alien Terror
	* February to May, 1999: 1 random mission, 1 Alien Terror~~, shooting down UFOs may trigger an Alien Retaliation mission~~		* February to May, 1999: 1 random mission, 1 Alien Terror
	* June, 1999: 2 random missions, 1 Alien Terror		* June, 1999: 2 random missions, 1 Alien Terror
	* Starting on the first month, each shootdown of a UFO can trigger a retaliation mission by the aliens, with the chance being determined by difficulty level		* Once an Infiltration mission starts on a region it will repeat itself indefinitely on that region, and it will keep spawning bases after all countries have signed pacts with the aliens
			* Starting on the first month, each shootdown of a UFO can trigger a retaliation mission by the aliens, with the chance being determined by difficulty level, at Easy being 4%, then increasing each difficulty level by 4%, until it reaches 20% on Superhuman
			** The chance of the Retaliation taking place in the region of the shootdown is determined by the formula (50 - 6 * getDifficultyCoefficient). If this fails the aliens will assign the Retaliation to a likely point of origin of the interceptor, based on its approach vector
			** There can only be 1 active Retaliation mission per region
	* After [[The Martian Solution]] is researched OR depending the difficulty level (March 2000 on Easy or November 1999 on Superhuman): 1 Alien Retaliation mission is added, in addition to the above		* After [[The Martian Solution]] is researched OR depending the difficulty level (March 2000 on Easy or November 1999 on Superhuman): 1 Alien Retaliation mission is added, in addition to the above
			** The detection chance for Retaliation missions is given by the formula: (completedFacilities / 6 + 15) / (mindShields + 1). Hangars count as 1 completedFacilities, not as 4
	* There is a 6% chance for a supply mission to be generated each day, for each alien base		* There is a 6% chance for a supply mission to be generated each day, for each alien base