Unlabelled a24? Doesn't sound possible; unless there's an issue upstream when packaging.
Here's what the package manager tells me:
# pacman -Ss 0ad
community/0ad a26-2 [installed]
Cross-platform, 3D and historically-based real-time strategy game
community/0ad-data a26-1 [installed]
Cross-platform, 3D and historically-based real-time strategy game (data files)
I could downgrade to 0ad a26-1 to match 0ad-data package, and I tried that too in fact, yet still same issue.