Hello, I have also encountered problems where the game suddenly crashes at between 40 minutes and 50 minutes when playing local game against 7 AI opponents. The error message was long and unintelligible (to me), but the last sentence suggested "Memory Error". I am using a Windows 11 computer with 16GB RAM in total, but only 7GB was used in total when the game crashed.
I made a Ubuntu virtual machine with 8GB RAM using VirtualBox and tried to play the game in there. It was very slow but the game never crashed. The maximum RAM usage was 6.4GB. Therefore I think the cause of crash is Windows version of the game has bug.
I have a solution for Windows users: @Barcodes
1. Set up a virtual machine running Linux operating system (choose a light distribution for example Lubuntu); allocate 8GB of RAM, 4 CPU cores and 40GB disk space to it.
2. Install 0A.D. inside the Linux virtual machine. You can find it at the first place in software centre or use the terminal command: sudo apt-get install 0ad
3. Host a game using your Linux machine, but put yourself (hosting you) as unassigned spectator.
4. To play, join your game from your real Windows machine as a guest player.
5. Press start from the virtual machine when you are ready.
Your Windows side will still crash after 40 minutes, but you now can simply run the 0AD game again from the Windows side then you can rejoin and play on without losing progress. The host cannot crash anymore, so at least you won't ruin the game for your friends.
After using this solution, I played against 7 AI again. My player Window crashed 3 times in the 2 hours long war but I did eventually win the game after rejoining.