I just added crew surrender during boarding combat and ran my final boarding combat test. I thought it might be interesting to post the events of the test as a boarding combat example.
Boarding Action
Launched by 1st Marine Regiment HQ and three Marine Battalions (66th, 67th, 68th). Attacking vessel is a Improved Omaha class Assault Transport with four Troop Transport Bays and four Combat Drop Modules and a maximum speed of 2530 km/s. Just before the drop, the attacking units are moved from the Bays to the Drop Modules. The target is an intact fuel harvester with a speed of 277 km/s. For the purposes of the test, the fuel harvester has been upgraded to strength-3 armour. The speed advantage of the transport is 9x so the number of D10 rolled for casualties is 11. While that might seem high, consider that while the target may be slow by Aurora standards, it is still moving 277 kilometres every second!
During the combat drop, the Regimental HQ suffers 80% casualties, the 66th Marine Battalion suffers 81% casualties, the 67th Marine Battalion suffers 50% casualties and the 68th Marine Battalion suffers 56% casualties. Note that by attacking from a faster ship or by slowing down the target. these casualties would have been far lower. It is probably a good idea for assault transports to carry low-powered weapons to slow a target without causing massive damage - or perhaps some type of anti-engine weapon could be added to the game.
During the Boarding Combat phase of the same increment, the fuel harvester's armour is checked. As there is no way in, the marines begin preparing a breaching charge. 30 seconds later the charge is detonated and a single armour box is destroyed. There are still two more layers of armour so two more breaching charges are detonated in the same location at 30 second intervals. Note that the attackers will not know the strength of the armour until they break through it. The damage caused by breaching charges is just like normal damage and shows up on a ship's armour status tab.
Once the armour has been penetrated, boarding combat begins. Each round of combat lasts for five minutes with the first round taking place five minutes after the armour is penetrated. During the first round, the total combat strength of the boarders, including the Marine boarding combat bonus and any commander bonuses, is 26.68. There are no defending combat units so the defence strength of the fuel harvester is based purely on its crew. With 610 crew, the defence strength is 6.1, giving a combat ratio for the attackers of 4.3738. This means a casualty chance for the defenders of 43.7% (10x Ratio) and for the attackers only 2.3% (10/Ratio).
As expected, the attackers do not suffer any losses. There are no defending combat units so the defending crew is checked. For purposes of boarding combat losses, a number of die rolls take place equal to the crew/100 (FRU), in this case 7. If a roll is equal to or less than the casualty chance then 1-50 crew are killed. In the first round of combat, the harvester's crew acquit themselves exceedingly well and only 37 are lost, leaving 573.
A surrender check is performed after combat if there are no defending combat units. The combat ratio is recalculated, which in this case is 26.68 / 5.73 = 4.66. If the combat ratio is greater than 5 then a number from 1-100 is rolled and multiplied by (combat ratio / 5). The result is compared to the average of the crew species' militancy and determination. If it is higher, then the crew surrenders and they, plus any officers, become POWs and are interrogated to gain spy points. In this case, the combat ratio is still less than five so the combat continues.
Crew resistance continues and remarkably they manage to inflict an 8% readiness loss on the Marine Regiment HQ while suffering just 8 more crew casualties. The morale of the Marine HQ is affected (not surprisingly!) and falls to 94.
Round three of combat begins 17 minutes after the initial boarding attempt. Attacker strength is unaffected by the HQ losses as the HQ has no attack strength anyway so it is still 26.68. There is still 565 crew on the harvester so the defence strength is 5.65 and the combat ratio is 4.77. The Marines finally get their act together and end their tentative probing. A full-blooded assault results in 108 crew casualties without further Marine losses. This changes the combat ratio to 5.84 so a surrender check is performed. The number rolled is 41. This is multiplied by (5.84/5), which equals 47.9. This is less than the average militancy and determination of the crew (67) so the fight goes on.
In round four a further 66 crew are killed, reducing the crew to 391. The combat ratio is now 6.82. 81 is rolled on the surrender check, which is modified to 111, well above the average militancy and determination of the crew so they finally surrender after putting up a brave resistance. 39.1 spy points are gained from the 391 surviving crew. There are no officers on board.
Steve