Angkor

The empire that engineered water
The Khmer built the largest pre-industrial city on earth in a floodplain that was underwater half the year and parched the other half. Angkor is a city builder about that problem, and about what you can raise once you have solved it.
Lay out roads and house plots, watch families move in and grow their homes, and keep the grain, stone, and labor moving. Every building has a walker; every walker needs a route. Get the layout wrong and your masons never reach the temple site.
A campaign in five reigns
Angkor Borei - A delta settlement at the mouth of the empire. Learn to work with water as it arrives.

Isanapura - Inland, from trade to rice. Dig the canal, fill the baray, and feed the fields from it.

Phnom Kulen - A plateau with no floodplain at all, but lots of sandstone.

Roluos - A network of reservoirs, gamboge trees, and wild elephants to be tamed.

Angkor - The capital. Command the flood, fill the great baray, and raise Angkor Wat from the ground up.

Features
Isometric cities in the Khmer architectural tradition

Water as a first-class system: canals, barays, reservoirs, monsoon cycles

Monument construction in stages, from foundation to blessing

Free play on any map - no objectives

Map editor: cut the rivers, plant the forest, build the empire you want

What this is, and isn't
Angkor is a small strategy game built by one person, not a genre epic. Five missions, roughly 6 hours, plus free play and the editor. No military, no combat, no diplomacy screens. Three city services and one water system, tuned deep instead of wide - closer to a focused Impressions-era campaign than a modern grand strategy.