Paradox has put on a promo for Millennia, probably to promote the Atomic Ambitions DLC.
Right now it is possible to play Millennia for the next 3 days until November 18 for free.
If you decide after this free play time that you need more, then you get also a 50% discount (until November 26) on the base game (19.99 instead of 39.99) and a 30% discount on the premium edition (41.99 instead of 59.99).
The free access as well as the discounts are available on the Steam page here.
Right now it is possible to play Millennia for the next 3 days until November 18 for free.
If you decide after this free play time that you need more, then you get also a 50% discount (until November 26) on the base game (19.99 instead of 39.99) and a 30% discount on the premium edition (41.99 instead of 59.99).
The free access as well as the discounts are available on the Steam page here.