Terra Invicta Dev Diary #8: Councilor Missions

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Terra Invicta Dev Diary #8: Councilor Missions

Post by johnnylump » Fri Apr 05, 2019 4:31 pm

Councilor Missions

In Terra Invicta, councilor missions are a key way to advance your faction’s goals.

Periodically, the game enters an assignment phase, and time is frozen while while all factions assign their councilors to a mission and a target for that mission. Targets can be other councilors, regions, nations, space facilities, alien facilities and other assets, habs, and fleets, among other things.

While taking missions, councilors travel automatically to any Earth location they are not prohibited from entering. Getting to space destinations for missions on those may take multiple turns.

Contested missions have a success chance based on your councilor’s attributes and the conditions surrounding the mission, and while assigning missions you may spend resources to improve your chance of success. Each contested mission type has a key councilor stat – typically persuasion, investigation, espionage or command – that sets up the base success chance.

Once you have assigned all missions, you may advance time again, and over the next few weeks missions are resolved in a set order, determined by mission type, with councilor attribute as a tiebreaker. The outcomes of missions can affect what happens in future missions, so you can chain certain mission types to maximize your gain, but your missions can also be interrupted by enemy action – such as your attempt to take control of Japan may be obstructed by an assassination attempt on your councilor.

In general, uncontested and defensive missions will occur first, followed by missions against councils, followed by contested missions that target regions, nations, and alien activities.

The success chance of a contested mission is determined by the difference between the acting councilor’s “attack” score and the target’s “defense” score. If they are equal, the success chance is 50%. As the difference increases, its effect on the success chance goes down via a diminishing returns mechanism, and it is not possible to get exactly a 100% or 0% chance to succeed.

In the attached image, a Resistance councilor is using the Control Nation mission to gain a neutral control point in Brazil. Brazil’s only defense is the size of its economy: It’s fairly large and complex, so this is a difficult mission.
missionUI.png
missionUI.png (123.82 KiB) Viewed 351 times
Meanwhile, the Resistance councilor has a Persuasion of 5 and a +1 bonus for her “Media Darling” trait, which is helpful in nations with a relatively free press (a Democracy score of 6 or greater), plus 0.2 more because the Resistance has a small measure of public support in the country. That gives a base success chance of 36%. Not so good. So the Resistance player has decided to spend some of the Influence resource to increase the success chance.

Resource spending starts at 1 unit (money, influence or ops) and doubles in cost for each +1 to the attack score. In the Brazil mission, spending influence increases the success chance like this:

+1 attack, cost 1 influence, success chance 46%
+2 attack, cost 2 influence, success chance 58%
+3 attack, cost 4 influence, success chance 68%
+4 attack, cost 8 influence, success chance 75%
+5 attack, cost 16 influence, success chance 81%
+6 attack, cost 32 influence, success chance 85%

The general goal here is to make the setting a difficult call via the aforementioned diminishing returns mechanism. (The precise calculation is the success chance is scaled by a value of 0.775 raised to the power of the difference between the attack and defense score).

If the roll is less than 10% of the success chance (so less than 7.5 for a 75% mission), it is considered a critical success and the council enjoys additional benefits.

A terrible roll in the top 10% of failure values (so the 97.5 or greater for the 75% mission) is a critical failure and the councilor will be in some trouble.

Here's an example of a post-mission report:
missionresult.png
missionresult.png (79.56 KiB) Viewed 351 times
The current design has about 40 missions, a few of which are only for the alien infiltrators on Earth. These include:
• Purge: Take an enemy faction’s control point
• Crackdown: Disable the benefits of an enemy faction’s control point and make it easier to purge
• Propaganda: Increase public support for your faction
• Coup: Attempt to overthrow a government, stealing multiple control points at once
• Hostile Takeover: Steal an enemy councilor’s orgs
• Turn Councilor: Turn an enemy councilor into a spy for your faction
• Sabotage Space Facilities: Destroy a nation’s boost and mission control resources
• Investigate Alien Activity: Try to discover what’s behind reports of alien encounters in an Earth region
• Assault Alien Asset: Attack a confirmed UFO landing, alien facility or other alien

In addition, councilors are attempting to operate in secret; when they complete a mission each faction makes a detection roll (using investigation versus espionage stats); if it succeeds, the councilor appears on the geoscape and may be targeted with some missions. Critical failures on missions tend to expose that councilor to easier detection, so it’s wise not to send councilors on throwaway missions with low success chances, as it puts them at greater risk.

Future dev diaries will cover: R&D, habs, armies and terrestrial warfare, ship construction, and space combat. Stay tuned!

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