Mission 3 - Raid on Spearhead
Last time I said it was possible to attack using ground forces but that it was unlikely to provide a faster result due to still having to deal with the huge navy that awaits. Plus ground troops and extra defensive buildings, and using weaker units than cruisers to damage the building, and being forced to take damage from the turrets that protect Rogoe's keep. Turns out it is possible, and faster, probably.
I wanted to improve this level because it is the longest. And as such tried several strategies because the navy attack didn't provide much faster results, I wasn't hitting perfect optimization but still. The main chokepoint is being forced to use two shipyards, if I could build my own it would definitely be easier.
First I did some testing to see how long would it take to take down the fortress with ground units, seeing how much damage each unit does and how many would it take to beat the shield and stuff. For those interested:
Troopers don't do damage to the shield for obvious reasons.
Mounted Troopers can't reach the target.
Grenade Troopers are advertised as strong versus shields, but nah, the target armor is factored in, and they aren't good versus buildings.
The mechs don't do enough damage as well.
You can build a fortress, but only Bounty Hunters.
That leaves the heavy weapons. Pummels, always the best choice, but they can't reach the target this time. That leaves artillery.
Final damage of a single unit:
Regular artillery: 34
Heavy artillery: 56
Fully upgraded artillery: 65 *
* Funny thing, Gungans have a technology which claims to further improve the artillery damage versus buildings. It did nothing (in fact it lowered damage by 1). So I only consider the Research Center's Heavy Weapons Engineers upgrade which adds 20% damage vs buildings, the final damage after building armor and stuff gives just a 16% increase.
Of note the heavy artillery improvement is definitely the better upgrade, as it improves not just the damage, and the damage upgrade is higher. Both become available at tech level 4 and from different buildings so nothing stops you from getting both.
Rogoe's keep shields regen based on current shields levels:
From 0-100 points it regens 2 points per second.
100-1000 - 4pps
1000-2000 - 8pps
2000-3000 - 12pps
3000-4000 - 16pps
4000-6000 - 20pps
As you can see, once you break certain point the damage per second you do starts to increase as the shields give in.
So one idea is to hit the keep hard to overpower the shields then destroy the keep. But another idea is to take down the shields so that instead of having negative damage output have extra damage. Once the shields are down the building's shield points lower by 40 points every second.
To understand this better I made a save with several artilleries and tested how long it took to perform each idea. Of course taking into consideration the time it takes to mobilize them. Destroying the shield generator (power core is too far) and then the keep was slower than just taking down the keep, provided you had enough artilleries to do substantial damage. The breaking point was 7 fully upgraded artilleries, they took the same time to do it either way.
7 FU art vs keep: 4:08
7 FU art vs shield then keep: same
14 FU art vs keep: 1:58
7 FU art vs shieds and 7 FU art vs keep: 2:30
Now FU artilleries take time and resources, you have to go to tech level 4 just for that. Knowing a tech level 3 artillery does half the damage, you'd be looking at 14 of those plus any other you could get in time to take down the keep. Most levels are completed faster if you just stay in tech level 3 (Pummels are best versus buildings and they are available then).
So in theory artilleries could do the job, had to get a game completed. The time for tech level 3 artilleries was 36 minutes, damn close to the Cruiser strategy of old...
Tried with tech level 4 artilleries, again 36 minutes.
Then tried something different, no artilleries, just upgrade range and turrets and build a lot and use them to attack the keep. In this case you must be tech level 4 because only advanced turrets do any damage to buildings. Same 36 minutes :D Another fun thing was that garrisoning troopers to increase the number of lasers added no damage, only "one" laser hit the keep.
In the end I went for using artilleries and then fully upgrading them during the attack, because in a real game there is little space to be using a mass of tech level 3 ones. Lasers could be made faster, maybe not.
Finally, killing the Boss while he says the city of all Gungans! triggers the end early.