Just an idea: Replace the spike "barrier" behind the statue with a stone gate, add a Forge behind the Stone gate, add a Barracks in the background, with a window revealing an Armory, and another statue resembling a Stickman praying (Temple)
Per upgrade, these buildings change,
the Barracks become larger (lvl 1) and a training field is added (lvl2)
The Stone gate's entrance gets a large gate (lvl1) and a drop off point for the miners is added to the side of the bastion (lvl 2, just a visual change)
The Stickman praying statue (Temple) becomes larger every upgrade
The forge becomes larger (lvl 1) and is more filled with gear (lvl 2)
Armory stays the same in every upgrade
All of this is purely a visual change, meant to enhance the experience

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