[colby]

No errors, but any reason why this doesn't work in game?

public something(id) {
    new origin[3],ent
    get_user_origin(id,origin)
    
    while((ent = find_ent_by_class(-1,"Player")) != 0) {
        
        new ent_origin[3]
        get_user_origin(ent,ent_origin)
        
        if(get_distance(origin,ent_origin) <= 200) {
            set_user_maxspeed(ent,0.5)
        }
        
        else {
            set_user_maxspeed(ent,-1.0)
        }

    }
    
}

[VEN]

maxspeed is in units. For example 250.0 is a default value for players. Set maxspeed to 1.0 to stop a player. maxspeed is reset on weapon change for players. Also it should be find_ent_by_class(ent,"player"))

[colby]

1. I've tried 100.0, 200.0, 180.0, none of them work.
2. I believe the default is 320.0.
3. I have this particular function loop every 0.1 seconds.
4. Having a lower-case "p" in "player" will cause the server to crash as soon as the function is called.

[VEN]

I've tried 100.0, 200.0, 180.0, none of them work

Your problem isn't maxspeed related.

I believe the default is 320.0

That's incorrect. Very many people think it's 320.0, but you should understand that entity max speed have nothing to do with the sv_maxspeed CVAR.

Having a lower-case "p" in "player" will cause the server to crash as soon as the function is called

Because you have infinite loop. Notice the text which i marked with the red color for you.

find_ent_by_class(ent,"player"))

[colby]

The server doesn't crash anymore, but it still doesn't work. I don't know if the default runspeed varies for different mods, but for TS, it is most certainly 320.

Here is what I have:

public something(id) {
    new origin[3],ent
    get_user_origin(id,origin)
    set_user_maxspeed(id,200.0)
    
    while((ent = find_ent_by_class(ent,"player")) != 0 && ent != id) {
        
        new ent_origin[3]
        get_user_origin(ent,ent_origin)
        
        if(get_distance(origin,ent_origin) <= 200) {
            set_user_maxspeed(ent,180.0)
        }
        
        else {
            set_user_maxspeed(ent,320.0)
        }

    }

}

[VEN]

You should say that it's for TS. Use ts_set_speed then.