If you are not aware, Activision is offering free PC Weekend that is going to end tomorrow on February 25 evening at 21.00 GMT. The game was highest grossing on the console in 2017 and it looks the developer wants new players to have a look at this action-packed first-person shooter video game. So all you need to do is download it from Steam client and start playing. New players who had not tested the gameplay yet can have a look at it game in detail. Whatever progress you had made during the free period can be carried forward in the full version if you decided to buy it.
You will not be losing your unlocks or your saved game content if you had ordered the full game after testing it out. This is one of the best thing players will not have to replay things back from start or worry about losing their object they are unlocked during the demo period.
This multiplayer trail can be a selling point for the game, it was able to maintain a very strong position from the date of release. You can try out the multiplayer mode, but there are no chances of having Zombie mode in the game. So if you really like you will have to spend money to get the full version with everything you are looking for.
If you had plans to buy the game you can get a 35% discount on regular price through steam. 25% discount is applicable on Deluxe Edition which is a part of a special promotion that will end on Feb 28, 2018.