GOG has currently a sale on various games from Blizzard and Activision. The main item of interest for us Civ-fanatics is the old “Call To Power 2” game, which had “Civilization” scraped from its name due to licensing rights, but is otherwise a very civ-like game and worth a look for fans of old games. “Call To Power 2” is currently discounted to 3.29€.
Otherwise the series of historical city builder starting with Caesar I to IV, Pharao, Zeus and Emperor is on sale as well. These games focus on building up your city in an ancient scenario, and are probably also interesting for some people. The price for these games reanges between 2.79€ and 5.09€.
You can find all these sales here: https://www.gog.com/promo/activision_blizzard_sale .