10 Hardest Video Game Genres To Make (From A Game Developer)
3. Physics-Based Online Games
A simplified explanation of how some online games function is: the server will expect you to do a thing, you'll do the thing, and it'll go "ding-ding-ding! Correct!" - it'll move you server-side (often ahead of your action), check your version of the game to make sure they're the same/it predicted correctly, then it'll confirm you're there on the server.
If you've ever been running along and zipped back about ten metres, it's because that "prediction" was incorrect; when you and the server desync, it moves you back to the last known location.
Not all games work this way, but this PredictoMax 3000 approach is excellent because it's so rapid, especially when characters and behaviours are predictable enough for it to work seamlessly. Characters only have a finite amount of movement options, walls are either being touched or not, and so forth. But what happens when you add the chaos... of physics?
Well, a total headache for your team's programmers.
The trouble with mixing physics with online gaming is that physics-based interactions are largely unpredictable until they actually happen. If you've ever been playing an online game with physics objects and shouted "whoa, did you see that?! That rock just missed my head!", and your pal replies "it was nowhere near you on my screen..." - then either the physics estimation by the server was different for both people, or the programmers were clever enough to make the physics objects unique to each player.
In any case, online games with physics are so difficult... because they're so unpredictable.