Protecting your Ramparts!
Your first step to success is to chose the right castle. Choosing one far from the water makes it more difficult for the troops to reach you, however, it also takes longer for your cannon fire to reach the enemy ships.
The best strategy in picking a castle is to chose one with lots of open space around it. Choosing one at the very edge of the screen will make is virtually impossible to repair in the later rounds. The castle selected in the above screenshot would be the WORST choice since it is surrounded by water and the edge of the screen. This would be very difficult to defend. Your best choice here would the one in the center. It gives you the most flexibility in terms of defense, rebuilding capability, and expansion.
To prevent the infantry from destroying the castle's heart, surround it on four sides by your cannons. While this won't prevent them from being an annoyance, it will keep your castle alive no matter what.
And don't be afraid to place cannons directly between two castles if they are both surrounded with the same walls. I find that it is easier to rebuild a large combined castle anyway.
It takes 2 cannonballs to destroy the brown ships, 3 to destroy the green ships and 5 to destroy the grey and red ships. Don't waste your cannon blasts and try to remember how many it takes for each ship to go down.
If there are red ships, blast them first. They cause the most damage and leave burning tiles that cannot be covered with new pieces. From this point, you should try to hit each ship at least one time to prevent any troops from popping out when they land ashore. Be sure to destroy the ships closest to your position to make sure that doesn't happen.
In the above screen, I am going after the red ship first. After that, I will blast the green ship which is deep in the bay, then move from right to left destroying the other ships. If done fast enough, you can hit each ship at least one time.
This is the most important phase of the game because it allows you to expand your territory. This territory is required to add more cannons, but it's also important to grab more castles as they will give you an extra canon for each one. The more castles you have the more flexibility you will be afforded.
Your castle walls are going to get hit no matter what you do. Don't try to repair what is already there, but place the parts AROUND the existing structure. This strategy is easier because you don't have to spend time thinking how to orient the piece. Just place it and move on.
Another thing to keep in mind is to keep the structure as simple as possible and try not to double up the walls. ("Checkerboard" damage can be really hard to fix!) Sloppy design will slow you down in the later rounds. Another thing to keep in mind is that the single blocks will be erased during the canon phase giving you more room. (Note the two single blocks in the middle of my castle? They will be gone in the next phase.)
After you have grabbed at least one castle, move away from your main structure and build a "dummy" castle. In the above screenshot, I was lucky enough to have the time to actually grab the lower castle, but I don't really care what happens to it. I'm more interested in drawing the enemy cannon fire to the dummy walls and away from my main castle. Another bonus to this strategy is that I was able to block off the enemy troops from advancing.
Lastly, don't be afraid to abandon your main castle. Capturing a single one will probably help you in the next rebuilding phase as more land will be cleared by cannon damage allowing you to reclaim it again.
There are two ways to get rid of them, and neither is very easy. You can surround them into your castle walls but this very hard because they keep moving around mucking up your plans. The other way is to blast them into oblivion with your cannons, however you risk destroying your own castle walls trying to hit those tiny targets.
If you have time, again, one of the best strategies is to build a defensive wall out away from your main castle. This will slow them from advancing.
Rampart is a difficult game, but ultimately
a rewarding one. It's a great feeling when
you're down to one castle and two cannons
and still survive the onslaught! The more
you practice these strategies, the better
warrior you will become.