Walkthroughs for custom maps.

In general, it's a tough situation, as I expected. If you're lucky and manage to hold out for a while, avoiding capture by the enemy, you can break through and win. In my case, Orange (Inferno) was stuck in place until I went there myself and dealt with him – it turned out to be easy. Purple later managed to emerge and capture some dwellings in the northwest, but didn't achieve much success. Brown was doing better: he had as many as 3 cities, but then he was beaten by both Turquoise and me, until he disappeared.
By the way, since you like playing with your brother in an alliance, you should try playing the map "2 friends" (it's in the collection of the best maps that I posted here, and I think I wrote about it on the forum). This is a map specifically designed for playing together in an alliance, although you can play it solo (as I did), but it will be a little more difficult and take more time.