Here are a few hints / commentary if you'd rather not see the full solution.
You start with 3 small bases near the center, 2 small bases in the NW, 1 small base in the SW, and 1 small base in the E. I was able to save a few of the outer bases on a few attempts, but was not able to consistently save any of them, much less all of them. The most viable strategy seemed to be to grow the 3 central bases together then try to build towards one of the satellite bases. In most attempts, I tried growing from center towards NW or SW, but every time, I was eventually crushed by one of the larger players on either side of my central merged base. (Some of these were blatant mistakes on my part but then I couldn't quite replicate what I had done the run before. Some I didn't notice any mistakes that I had made but I was just outmatched and clawing to stay in the game until I finally called it quits.) Ultimately, I found a solution which involved joining center + E bases, which was odd because it seemed the hardest connection to make. Maybe I just got luckier on the run that ended up being successful.
On turn 1, I merge 2 center bases and build a castle. I tried various places for the castle before finding one I liked. I didn't explore not building a castle very much, as this base will get attacked from all sides fairly quickly. I grow the satellite bases as long as I can but I never managed to build a castle in any of them. On turn 5, I built another castle in the center base, which is only 2 hexes away from the 1st castle. I normally like spacing them out 3 hexes apart, but this seemed like the best way to grow and hold territory when all sides are pressing me (but only with L2 spearmen). Also on turn 5, I took a risk with my E base that panned out. I killed an enemy town hall to starve a rival L2 spearman, leaving a tempting target for another player to destroy my own town hall (but not immediately starve my L2 spearman as a result). The risk panned out and my E base survived. On turn 7, I merged my central base to the 3rd base near the center and started trying to grow E, while I tried also to move W from my E base (but without building a castle). My other 2 satellite bases were still alive at this point but it was clearly only a matter of time before they died.
I first attempted to join center + E base on turn 9. It was risky. Yellow could upgrade to an L3 knight and destroy some troops and break the connection, which he did, but I re-connected the bases on turn 10 via a smaller player's territory. On turn 11 I solidified the connection with my first L3 knight.
I then spent many turns trying to subdue, starve, or intimidate other players in the E (yellow and dark brown in particular), and in the meantime, dark green had wiped out my SW and NW bases and was growing unchecked in the W, and had no borders to worry about other than his (longish) front line. By turn 18, I had managed to defeat yellow, intimidate dark brown, and was starting to deal with light brown, but now dark green was starting to nibble at my territory and I had to do something about it.
Turn 19 was pivotal. I saw an opportunity to take a small chunk of dark green territory while then fully guarding my entire border with dark green via 3x L3 knights. (In particular, I set myself up to be able to guard this chunk of newly captured territory with a single castle, planning to leave it there and grow/attack elsewhere.) He could have upgraded to an L4 super knight right then and done serious damage to me, or he could have played defensively and guarded his border with L3 knights while growing elsewhere, but I correctly predicted he would do neither, because he could instead devour virtually all of light brown without upgrading troop levels. He took the bait, committing his entire large army into one thrust attack to completely demolish light brown -- and left himself completely open to letting me starve his entire army. He was still the larger player at that point, and immediately built an L4 super knight to rejoin the territory I had cut off, but as usual, that didn't prove very effective and I was able to starve his army many times as I consistently pushed forward to take more and more chunks of his territory safely. Dark brown had remained dutifully cowed for 14 turns and was now ready to be digested.