Paradox Interactive are notoriously enthusiastic about DLC, often releasing years of expansions and add-ons for their big strategy games rather than leaping straight into sequels. So as an alternative to spending £100-odd for all a game's DLC, Paradox have started dabbling in letting players pay monthly fees to play them. The next game to start such a DLC subscription service is Hearts Of Iron IV, launching today. Like the others, it'll charge £4 per month. Or alternatively, you can still just buy DLC for keepsies.
The subscription service is now live on Steam, costing £3.99/€4.99/$4.99 per month, with small discounts for buying multiple months at once. It offers access to all the expansions plus the Sound Packs and Cosmetic Packs which add new music, speeches, models, and skins for extra flavour. That's currently £120-odd bought individually, though of course it goes cheaper in sales.
Paradox say all upcoming expansions and content will be added to the subscription (as well as still sold normally). But yeah, you do need to buy the base game separately on top of this.
"With a plethora of DLC options to choose from, starting out from scratch can be daunting to new players," Paradox say in the FAQ. "This is an affordable way for players to experience the entire HoI4 catalog without having to weigh which items they would prefer to purchase."
That's true, but you could also read reviews and wait for discounts in sales. Especially when much of HOI4's DLC is ehhh.
As Paradox continue launching sub services, this individual approach does look less and less attractive. Moreso when, unlike CK2 (which offers the base game free), you have to buy the game too. And especially when you compare it to the (possibly unsustainable) quantity of games you get on Microsoft's sub service, Game Pass. Maybe Paradox are missing a trick by having per-game services rather than an all-encompassing Paradox Pass or whatever. Presumably they wouldn't still be launching a new sub service if the old ones weren't successful enough, but I know which service I'd be more interested in.