AI War:How Exogalactic Strikeforces Work

• Note: this information is current as of version 5.018.

What are Exogalactic Strikeforces?

• Exogalactic Strikeforces are special attacks sent by the main AI command in the other galaxy.
  • More technically, an Exogalactic Strikeforce is a specific kind of "Event Attack". The Event Attack mechanic is also used for the chase groups in the Fallen Spire campaign, and the special defense forces spawned on AI Homeworlds in the Fallen Spire campaign.
• All exogalactic strikeforces make a beeline to a player's home sector.

What causes Exogalactic Strikeforces?

• If Minor Faction "Broken Golems - Hard" is enabled, the threat of functional golems in human hands provokes this kind of response. In this case, the frequency of the strikeforces increases as AIP increases.

• If Minor Faction "Spirecraft - Hard" is enabled, the threat of spirecraft in human hands provokes this kind of response. In this case, the frequency of the strikeforces increases as AIP increases.

• If Minor Faction "Fallen Spire" is enabled, and at least one Spire City has been completed, the threat of the Human-Spire alliance provokes an intense exogalactic response. In this case, the frequency of the strikeforces increases as the number of Spire Cities increases (the more buildings a city has, the higher the increase, but going long-term with an "incomplete" city isn't really going to help you). It also increases with the presence of the Galactic Capitol when it is constructed. Finally, if the Exogalactic Transceiver is constructed the frequency of strikeforces jumps through the roof in a very, very unpleasant fashion.

• If you lay siege to the enemy core homeworld, the AI will send a strikeforce in 10 minutes, and every 30 minutes thereafter until the siege is complete.

How is the size of an Exogalactic Strikeforce determined?

• The "raw budget" in points varies by the source of the provocation.

• For "Broken Golems - Hard":
  • The first "exo-wave" has a raw budget of 13,000 points.
  • Each wave after that is 25% bigger than the previous wave.
  • The maximum raw budget is 110,000 points.

• For "Spirecraft - Hard":
  • Currently the calculation of point budget is exactly the same as the golems case. But note that if you have both enabled that both will "charge" and send exo-waves separately.

• For "Fallen Spire":
  • The first provoked-by-existence-of-completed-spire-city (i.e. NOT counting the chase groups spawned during shard recovery or during the construction of a new city) "exo-wave" has a raw budget of 10,000 points.
  • Each wave after that is 25% bigger than the previous wave.
  • The maximum raw budget is 60,000 points times the number of spire cities plus 60,000 if the galactic capitol has been built (so if you have 5 cities and a galactic capitol, the max is 360,000 points).

• To get the actual effective point budget:
  • Multiply by difficulty modifier:
    • use the higher of the two AI player difficulty numbers.
    • if Diff < 7, then Diff * 0.15.
    • else if Diff = 7, then 1.
    • else if Diff <= 9, then 1 + ((Diff - 7) * 0.5). (Ex: if 8, then 1.5. Ex: if 9 then 2)
    • else if Diff <= 10, then 2 + (Diff - 9). (Ex: if 10 then 3).
  • Multiply by AI handicap modifier:
    • use the higher of the two AI player handicap numbers.
    • if Handicap <= 0 (0 is the default), then 1.
    • else, then 1 + (Handicap/100) (Ex: if handicap is +40%, then 1.4; if handicap is +300%, then 4.0)
  • Multiply by number of human homeworlds or number of active human players, whichever is greater.

How is the timing of an Exogalactic Strikeforce determined?

• Each game-minute (not necessarily on the :00 second, but once a minute), an amount is added to the "AccumulatedEventWaveCounter" for each active source of exogalactic strikeforces. When that counter is greater than or equal to the target raw budget (calculated above), the strikeforce is spawned with the counter's value as the raw budget (meaning that the raw budget is generally at least slightly higher than the actual target) and the counter is zero'd out.

• The amount added to the counter depends on the source:

• For "Broken Golems - Hard":
  • The counter is incremented by the current AIP or the "alternate minimum AIP", whichever is greater.
    • That alternate minimum, or "AMP" is computed by (Game_Time / Divisor) where:
      • Game_Time is the current number of seconds elapsed in the game thus far, or 15 hours, whichever is less.
      • Divisor is 360 on Diff 8 or below, 330 on Diff 9, and 300 on Diff 10 (with 8.3 getting about 350, etc).

• For "Spirecraft - Hard":
  • Currently the calculation is exactly the same as the golems case.

• For "Fallen Spire":
  • The counter is incremented by 1000 * the number of spire cities plus 1,000 if the galactic capitol has been built.
  • If the exo-galactic transceiver has been built (not during the building of it, but after it has been fully constructed) then the counter is *multiplied* by 1.5. Since this happens every game minute, that means the strikeforces will be coming in really rapidly.

How is the composition of an Exogalactic Strikeforce determined?

Time constraints preclude a completion of this article right now, but there's a lot of info on event-attack composition in general in this Fallen Spire article.

One important point for this article is that the Golems and Spirecraft variants have a certain chance to use an alternate allocation that puts more of the budget into the lead ship, and/or concentrates the whole strikeforce into a single battlegroup.