Blizzard are hosting another Overwatch free weekend, where every hero, every map and every other bit of content will be available, minus the cosmetics which are acquired via loot boxes. That said, free weekenders can also get those.
Overwatch's free "weekend" will run for four days, from 23 to 27 August 2018 on PC, PlayStation 4 and Xbox One. Blizzard have cited the last free weekend's being only on PC as a reason for another free weekend so soon.
All progress made during the weekend will carry over if the players purchase a full copy of Overwatch afterwards, including any loot boxes they get during that time. This includes the new Summer Game loot boxes as well.
The weekend will start at different times, depending on players' time zones. For North and South America, it will be 11:00 AM PDT on 23 August 2018, for Europe 20:00 CET on the same day and 02:00 AM CST on 24 August 2018 for eastern Asia.
Technically, the official post lists pre-loads as a possibility but they will not be available until 23 August 2018 for PC. Pre-loads are already available for PlayStation 4 and Xbox One though. PS4 users will need to go to PS Store, search "Overwatch", click the "Free Weekend" button and download the game. Same goes for Xbox One, except they will need to click "Overwatch: Origins Edition" and then "Free trial" on Xbox One store.
Free weekends usually have a 50 per cent off sale during and after the event, but Blizzard haven't announced anything like that yet for this weekend. It is not excluded that the discount will still happen, but at the time of writing there is no official confirmation.
Bear in mind that Overwatch does not support cross-platform gaming so if you have a buddy on a different platform, you will not be able to try the game together. Or at least not from the same lobby. Hammond, the newly added hamster will be available as a playable hero during the free weekend.