[yugecin]

If a player is paused, he won't send updates anymore, so you can for example keep a variable for every player that tracks the last update, and if the current time subtracted by that last update is some amount of seconds, the player is afk.

Code:

new lastupdate[MAX_PLAYERS];

public OnPlayerUpdate(playerid)
{
    lastupdate[playerid] = gettime();
    return 1;
}

isPlayerAFK(playerid)
{
    return gettime() - lastupdate[playerid] > 3; // afk if player hasn't sent any updates for 3 seconds
}