Is it possible to prevent application decompilation?

Question

Unity

I read in various sources about the decompilation of applications. On many I met such phrases as "it is possible", "not quite everything but it is possible", "there is no hierarchy to get, but you can read everything in scripts".
From this question: is it possible to somehow make it impossible to decompile applications and make it impossible to see what is written in the scripts?

This is mostly a question of how to write an application (if it is online). The data is stored on the server. But if you can open the application and send the "necessary" data to the server, then you can cheat in such a way that few people will like it.

Or make the application itself so that it cannot be opened and the data can be changed, as well as requests to be encrypted. Or secondly, on the server itself, check the received data and compare whether such changes are possible ...
And, right there, on the topic: how does a photon relate to this? Does he encrypt something and recheck it?

Ps - of course, at the moment there is no question of security, but for the future ... maybe the scripts themselves will need to be written differently ...

Answer 1

Everything that runs on the client can be hacked

Answer 2

The only way to guarantee protection against hacking is to send the final 'picture' to the client, and send the client's actions from the client. A degenerate case - players connect to your server with something like remote desktop (such a possibility has appeared in game engines for a long time).
Of course, there is no need to transmit exactly the image, it is enough to broadcast limited information about the objects of the world, only what is needed for display - coordinates and state (for example, the player's pose), but you can not transmit information about objects that the client does not see (then it will not be possible to see enemy 'through the walls').
The disadvantage is some development complexity and sensitivity to network problems (users will be uncomfortable playing on lags).
Everything else can be hacked, traffic analyzed. Of course, you can make it as complicated and expensive as possible, but this will complicate development for you.