Luckily the Game community is pretty open on how technology works, Horizon New Dawn programmers have done multiple videos on their technology. This is interesting because they converted a simple save game system like used in Kill Zone to something much more advances like is used in Horizon New Dawn.
[https://youtu.be/ucTeAWv5DX8?t=951](https://youtu.be/ucTeAWv5DX8?t=951)
[https://youtu.be/ucTeAWv5DX8?t=1879](https://youtu.be/ucTeAWv5DX8?t=1879)
TLDR; Horizon New Dawn: All important objects are stored in Database, everything not is not stored
Kill Zone: Every object position / status is saved out to save game.
Latest Answers