Hi. I would like to know somethings about games I've got some titles like assassin's Creed and watch dog. before i sign up for stadia i need to know if I can ad them to my stadia account and play them or would I have to buy them again?
Stadia is not a "virtual PC" in the cloud. It is more like a cloud console. The point is, it is a separate ecosystem, more like Xbox or Playstation, and just like those, buying a game for one ecosystem doesn't let you play it in another. Games have to be ported to each ecosystem and supported by their developers and publishers, and that costs money. But, if you do buy a game for Stadia, you can play it on Stadia as much as you like – no subscription is required (unless you want to take advantage of 4K resolution and surrounds sound). I hope this answers your question.
In addition to what was said by @JohnZoidberg
If you have a Ubisoft+ account you can link it and access different Ubisoft games on Stadia, without having to buy them again.
Stadia is not a "virtual PC" in the cloud. It is more like a cloud console. The point is, it is a separate ecosystem, more like Xbox or Playstation, and just like those, buying a game for one ecosystem doesn't let you play it in another. Games have to be ported to each ecosystem and supported by their developers and publishers, and that costs money. But, if you do buy a game for Stadia, you can play it on Stadia as much as you like – no subscription is required (unless you want to take advantage of 4K resolution and surrounds sound). I hope this answers your question.
In addition to what was said by @JohnZoidberg
If you have a Ubisoft+ account you can link it and access different Ubisoft games on Stadia, without having to buy them again.