The sounds remind me of "Stronghold: Crusader". In terms of suggestions, making the soldiers look different based on their upgrades would add more realism and impact to the upgrade system.
Perhaps the next step would be to add a perk/skill tree system. This will further diversify the gameplay and give players more strategic customization options.
The red exile ships dont seem to die after their health bar is gone, if this is intended due to some kind of a shield, then it would be helpful to show the shield hp bar also, otherwise it seems like a bug in the game
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