Optional Convoy Mod Synchronization

[Deebz__]

I am requesting the addition of a checkbox, visible to the host of a Convoy session when they are creating the session: Enforce Mod Synchronization

If this checkbox is disabled, users will be allowed to join the session with any mods that they want, without needing to load the same mods as the host. Users who join a session with this disabled will be presented with a warning, that there may be possible issues if their mod list is different than the other users in the session.

I want this option to be added because it will allow me to play with my friends without giving up any graphics, UI, sound mods, or anything else which will cause no issues at all for the session if my friends do not have the mod.

Could other types of mods cause issues with desync? Yes. However...

This will NOT be as problematic as you may think.

In fact, it may even be LESS problematic than forcing the synchronization of mods to happen. Installing/uninstalling random mods can lead to save game corruption.
Allowing users to play together with different mods WILL NOT lead to savegame corruption. It does not even lead to game crashing, or anything similar.
In short, this option would be safe.

As I am sure SCS knows, there were multiple ways for users to bypass the "no mods" restriction in version 1.41 of the game. I, along with some friends, used these opportunities to do extensive testing to see how well the game worked with various types of mod desync. This is what we found.

There are 3 main areas that can be sources of desync related problems in multiplayer, and the game already handles most of the issues. In the spoilers below, I cover what the issues are, how the game handles them, and provide solutions to a couple of remaining problems.

1: Another Player's Truck/Trailer
The game already has a system in place to handle what happens if a non-modder's game is unable to render an essential component of a modder's truck or trailer, such as a chassis or cabin. The game simply auto kicks the modder. This logic is inverse if the session host has a custom truck. Anyone without the truck or trailer gets auto kicked instead.
The auto kicking is actually unnecessary, and was added after 1.41 left beta. During the beta, the modder's truck AND trailer would simply appear as invisible to players who could not render either one. They were still there on the GPS, traffic still saw them, and you could still hear their engine (assuming it was a vanilla engine at least), but you could simply not see them in the world. At the time, the modder could be shoved aside by players who could not see them, but this could be resolved by simply disabling collision with those other players.

Either solution can work to mitigate issues with truck/trailer desync.

Non-essential components like paintjobs are simply replaced by default ones. The truck will still appear without them.

2: Traffic
There are two desync-related issues that can come up. A custom model, and traffic location desync based on map mods.

With custom models, SCS already substitutes the model that the traffic car uses on the non-modder's screen with another one. This approach can possibly lead to issues with players hitting a traffic car on one person's screen, but not another. A safer solution would be for SCS to simply delete the mismatched traffic car from the road, as they already know that the traffic car cannot be correctly created on another person's screen.

With location-based desync, traffic are ONLY synchronized on roads that exist on both player's screens. If one person has a map mod that adds new roads, they will see traffic on those roads, but other players will not. The issue comes in when traffic drive onto roads that are shared between all players, and suddenly pops in out of nowhere for players without the mod. The game already deletes a traffic car if it appears inside of another player's truck. SCS can add an additional safeguard here by deleting any traffic car that will spawn within a certain range of another player. This system is ALREADY in place for randomly generated events after some later 1.41 betas, and should be possible to easily extend to traffic spawning. Not only would that solve issues with mod desync, but it would solve issues with convoy in general, as this can happen during a normal session already thanks to network desync.

Other types of traffic mods, such as traffic behavior mods, density mods, traffic light duration mods, etc, have no desync issues at all. Individual traffic cars and intersections are controlled by one player, and they are synced over the network to other players. This is necessary for Convoy to work, and resolves mod differences on its own.

3: Job sharing
...well, this work is already done thanks to DLC mismatches. Players who lack the cargo type, or cannot reach the start/end point of a route, cannot take the job. Ez.

Other issues are so minor that they aren't even worth mentioning. You may see someone floating in mid air if they have a map mod that you do not have. So what? If you both want to explore the same map mod, you will both still need to install the same map mod. This is common sense.

In the end, strict sync is unnecessary and potentially harmful to the experience. In the worst case, it can even lead to profile corruption, as SCS themselves point out in the UI. Mod desync issues are far less severe, and won't even be an issue among friends who know what they are doing. They barely even need to be an issue among people who do not know what they are doing. Convoy was always intended to be "friends playing together", even according to SCS. The argument for mod sync may hold more water if Convoy were a larger scale multiplayer mode, but it simply is not. Modding freedom should reflect this.

One final point for SCS tech support.
Savegame corruption will, and already has, happened due to forced mod sync in the 1.42 beta. It would not happen due to mod desyncs caused by the option I am proposing. Would you rather deal with more save corruption cases, or have some of them come in like: "The game said I was kicked from a session because I have a mod truck. Help!"

Save corruption is no doubt more tiresome to troubleshoot. A simple mod desync would be an open and shut ticket.

[TwinShadow]

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[Deebz__]

I don't like the choices in this poll because it's not unbiased with simple yes/no/neutral answers. You're baiting people into voting one way for your own gain.

That aside, either way I'm not for this. Mods are already a risk to run in a normal game anyway, and are technically not supported by SCS in the first place. I would rather everyone in a session have the same mods, as it is now, before anyone can join in. I only want to play with select friends anyway, and handing them a drive link with all the mods is not that big of a deal for me. Course, this isn't for everyone, but allowing players to join in with whatever mods and you run into the real possibility that SCS has to account for a billion different possibilities in modding that I don't know if they have the resources to account for.

The choices are objectively true. As I outlined in detail with my post, forced mod sync can (and already has) led to profile corruption, while making the mod sync optional leads to comparatively minor issues with no possibility of profile corruption. I stated the main upside and downside with both options.

As for the rest of what you said, there really aren't a billion different possible points of failure here. Only a few types of mods matter at all to what other players see, and I cover those here. I also hope your friends don't have any favorite graphics/sound mods they wouldn't want to play without, which you wouldn't want to use. There would be no problem if each player used their own mods of those sorts, among many others. That is one of the many problems with strict mod sync.

[Frayner]

I half agree with this, purely on that some mods would need to be synced with others.

Mods that don’t affect others, like HUD mods or dashboard display mods you could get away with not syncing them, but other mods like truck or map mods, or even skin mods should be synced with other players.

It should really be on a mod by mod sort of basis really.

[Deebz__]

I half agree with this, purely on that some mods would need to be synced with others.

Mods that don’t affect others, like HUD mods or dashboard display mods you could get away with not syncing them, but other mods like truck or map mods, or even skin mods should be synced with other players.

It should really be on a mod by mod sort of basis really.

This would be ideal, however SCS have stated that they are unable to tell which mods would be safe and which ones would not be. In the lack of this option, I feel that letting session hosts choose whether or not to force the sync of mods should be optional. If it's off, users will need to be responsible for using the same custom trucks/maps as each other. However, fail safes should be (and mostly already are) in place, just in case.

[Frayner]

Yes exactly. Though maybe they could come up with a way for modders to be able to tell the game through their mods if it is a mod that needs to be synced in multiplayer, or if it’s a mods that you can get away with not syncing.

That way the game could read the mod and be like this one is safe and doesn’t need to be synced and then it would tell you that a different mod needs to be synced.

Sort of something to streamline the process, though I’m aware it could take a lot to implement something like this.

[Deebz__]

The only issue I could see with this being mod-sided is that it would be fairly trivial for an end user to change the setting, and join a session with a mod that really should be synced, which may lead to issues the host of a session would rather avoid. However, with it instead being an option for the session host, this would give the host complete control over how they want their game to work. Any host who disables the option should be fully aware of the advantages and disadvantages, as should anyone who joins that session.

However, I would be all for any solution that works to allow inconsequential mods to be freely used. I just proposed the simplest option I could think of that SCS may try.

[Some newbie driver]

Though maybe they could come up with a way for modders to be able to tell the game through their mods if it is a mod that needs to be synced in multiplayer, or if it’s a mods that you can get away with not syncing.

SCS can't in any way rely that a random mod creator had done right the due diligence of checking the suitability of its mod for MP and stated it correctly in the manifest. Think in all the problems that had been here, in the help sub-forums, when one mod allegedly doing A affected also B in the background just because the original modder initially wanted to do A and B and later forget to remove B in newer updates.

If we ignore what the modder say, then the game should need to automatically understand what a mod does in order to allow it or not. Then we are talking about very good AI routines on a game so limited in CPU usage that cannot apply a complete way simpler AI traffic control. Not to mention that people is complaining now because the game takes 15min to check their bloated 300+ mods folders. What about 15 hours, or days? I'm sorry Frayner, but SCS is completely right in that: it's an all in or all out scenario.

In general and theoretical terms, I agree with the terms proposed by Deebz__. If the game can sort the problems from heterogeneous mods or if those problems are not something critical; there could exist the option for people to decide. But if we port that to reality, we have that:

A: People don't read, don't know and don't care what they do with the game already, as to give them that smoking gun. You said those complains can be ignored, but I don't blame them for not even want to hear about them.
B: I don't think any video game company wants to give their players, from start, an option that ensures that players are going to suffer weird game behavior. Maybe in the future, but not now.
C: Also it would be impossible to do a proper debug of the system that it's starting now if they had to consider the effects of mixed mods
D: Also something to consider is the media perception created with the update. The last any company wants is that Internet ends filled with images and glitches of a game working wrong and without the proper context to explain that image.Maybe in the future, but not at launch time or the perception the public could have is that the release has been a complete disaster.

Last but not least, as we have not a complete understanding of all the details of how the game works; I'm not entirely sure that picture of "relative harmless" effects of mixed mods is 100% accurate. We can be pretty sure that some category ones could be, as they should not alter the shared info in a MP session. But I've my doubts with what can be properly checked and what not regarding maps mods for example in order for the game to decide those safeguards.

They have chosen the safest path from the game stability perspective and I completely agree with that when we are IRL and not in the theoretical plain of things. Profile corruption isn't a problem of MP, it's a problem of modding, plain and simple (thousands of examples only in this forums to prove it). So, anybody who uses mods should sign with blood and informed consent about it. At this moment, the best I can think they could add to the game is an auto-backup and recovery system for the profile each time one enters a modded MP session; just because the odds are higher and people are too excited to try it to cold-minded think in the possible cons.

Regards

[Zakxaev68]

No matter what everyone says, mod syncing may not be an issue at first sight, albeit it's much more evident when a lot of people use mods you can't/won't obtain due to some mod-makers decision. I'm talking paid content certain people refuse to play without. In turn, the whole thing should be made optional for the player to choose whether he wants to have the same mods and save himself some risk or play with his own mods on the cost of few crashes. Save corruption can EASILY be prevented, it's called "backup your common sense* - *=save". Games don't break themselves, players often forget it's them doing it.

[TwinShadow]

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