Aliens Boardgame: Sentry Guns

Leading Edge’s Aliens Boardgame doesn’t feature any rules or mention of the Sentry Guns seen in the Special Edition of the movie, however their miniatures line did produce figurines of these automated weapons.

Even though they’re not used in any of the original included scenarios, I decided to create “Marine cards” for the Sentry Guns so that they can be utilized in custom scenarios. Once such fan-made scenario is detailed below.

Note that these cards have no “Wounded” side since Sentry Guns can’t really get wounded, IMO, just destroyed.

The following rules and scenario are heavily based on those designed by Mick Lee (with help from David Gonzalez Rice) here.


Sentry Gun Rules:

Each Sentry Gun has 3 Actions which can be spent to either shoot (as per normal Marine firing rules) or “Cool-Down”.

Sentry Guns fire like Machine-Guns, including using the Machine-Gun’s Special Ability (see original rules, Section 3.2, page 26).

Every time a Sentry Gun fires, it’s Heat increases by 1. When Heat reaches 10, the gun has overheated and cannot fire.

Each Cool-Down action decreases that Sentry Gun’s Heat by 1.

Sentry Guns can fire even when they have no Actions left, however each “bonus” shot increases Heat by 1 and the Player must roll 1D10 immediately; if the roll is lower than the gun’s current Heat, it overheats (set its Heat to 10).

Sentry Guns can only shoot or Cool-Down. They cannot move and are unable to initiate a Melee attack.

Optional Rule: Auto-Targeting

For an added challenge, using this rule, all Sentry Guns must declare their targets before anyone (other Sentry Guns and Marines) fires. This means that if two Sentry Guns target the same Alien and one kills it first, the second Sentry Gun’s shot is wasted. Use the Targeting Markers below if needed.


NEW SCENARIO: Shooting Gallery

To play this, use the awesome “Corridors” Map created by Mick Lee (see below).

  • Set-Up
    • Marine Player(s) place 4 Sentry Guns on the spaces marked A, B, C and D.
  • Sequence
    • Aliens Move
      • All Aliens move 4 spaces towards the nearest Sentry Gun.
    • Aliens Appear
      • Each turn, roll 1D10 for each of the two corridors to see how many Aliens appear. Roll once for each corridor.
      • Roll 1D10 for each Alien that arrives to determine their starting space, using the numbers on the squares to place them.
      • If you run out of Alien tokens/models when required to place them, for every Alien you can’t place, one Alien already on the board gets an extra activation (i.e. move 4 squares and can attack).
    • Aliens Attack
      • Any Alien that reaches a Sentry Gun may attack as normal. Results of anything other than “In Combat” or “Alien Loses” means the Sentry Gun is destroyed and removed from play.
      • Acid Splash effects Sentry Guns; a result of Incapacitated or Dead destroys the Sentry Gun and removes it from play.
    • Marines Move/Fire
      • Sentry Guns each spend their Actions firing and/or cooling.
      • Sentry Guns cannot move or initiate a Melee attack.
  • Victory Conditions
    • If two or more Sentry Gun survives to the end of the Turn Chart (i.e. 15 Turns), the Scenario is a Draw.
    • If only one Sentry Gun survives to the end of the Turn Chart (i.e. 15 Turns), the Scenario is a Draw.
    • If all Sentry Guns are destroyed, the Players Lose.
  • Movie Summary
    • Wave after wave of Aliens rush the four Sentry Guns, ignoring heavy losses. Three guns run dry but finally the Aliens stop and retreat. In game terms, the Scenario is a Draw.

Note #1: If you are playing the Movie Scenario (i.e. a series of linked Scenarios), play the “Shooting Gallery” scenario just before “Operations & Air Ducts”.

Note #2: if you are using Victory Points to keep score in a series of linked Scenarios, consider each Sentry Gun that survives to be worth 1 Victory Point each.


Using Sentry Guns in Other Scenarios:

Depending on the scenario being played, decide how many Sentry Guns the player may place.

  • Two suggestions for the “Operations & Air Ducts” scenario, if you playing the Movie Scenario (i.e. only using survivors from the Reactor Room scenario, plus Gorman, Ripley, Newt and Burke):
    1. For each Marine less than 7, take one Sentry Gun.
    2. Take 4 Sentry Guns. For each extra Marine over 7, discard one Sentry Gun.

You may choose to set up the Sentry Guns on the current Map before play begins, or place them “outside” the Map in order to kill Aliens before they reach the map.

If you place a Sentry Gun “outside” the map, discard it but reduce every Alien drop during the following scenario by 1. Do this for each available Sentry Gun you “discard” in this manner (i.e. two Sentry Guns deployed “outside” = reduce every Alien drop by 2).

If you choose to place Sentry Gun(s) on the Map to use during the Scenario, they may be placed in any space but cannot move once the Scenario begins. Use the above Sentry Gun Rules during the Scenario for actions, firing and Heat.


My Sentry Gun Cards:

Note: I made these cards quite a few years ago, long before I discovered Mick Lee’s rules/scenario; because I like his “overheating” concept so much, I may redesign these cards to provide a way to track Heat for each gun too.


Mick Lee’s “Corridors” Map:


Mick Lee’s Sentry Gun Cards (and tokens):



Again, full credit and huge thanks and credit to Mick Lee (and everyone else in that BoardGameGeek thread who helped) for the Map, tokens, scenario and rules.

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