Action Replay Justice

It is a sad fact that cheating and rule-breaking in sport gives rise to a lot of bile amongst both competitors and supporters. Think of the furore when a top athlete fails a drugs test, or when the result of a championship final comes down to a judgement call about offside. Multiplayer computer games are no different, and while there may be some rough team sports out there, in no other setting are team players so overtly trying to beat the crap out of each other as in an online first-person shooter. Throw in a bit of teenage angst in 1/3rd of the player base and you have a massive “bile bomb” primed to explode at any moment.

For this reason, cheating and the perception of cheating is a really big deal in the design of online shooters. In Boom! Headshot! I voiced some theories of mine on how a lot of the perception of cheating in computer games may be explained by skilled players inadvertently exploiting the game mechanics, but I have recently seen a shining example in the form of the game Call of Duty 4: Modern Warfare (COD4) of how to address and mitigate the perception of cheating.

First lets review two sorts of cheating that have really captured the imagination of the popular player base: wall hacks and aimbots. With a wall hack, the opponent can see his target even though he is concealed behind an object because the cheat has modified the graphics drivers to display walls as translucent rather than opaque (slight simplification). Aimbots can identify enemy players and assist a cheat in bringing his rifle to bear on the body of the enemy, usually the head. Many players who meet their death in situations where they cannot see how the person has managed to hit them (because they have been hiding, have been moving evasively, or are at great distance) get frustrated and let rip with accusations of cheating. Ironically this sort of cheating is pretty rare, because widespread adoption can be effectively countered by cheat detection software such as punkbuster. There will always be one or two cheats with their own custom software, but the masses simply cannot cheat.

But the trick the Call of Duty 4 developers have used is to make an action replay. Now this has been done before in games for dramatic effect, but crucially COD4 makes the replay from first-person view of the enemy who makes the kill, and winds back a full 5 or 6 seconds before the kill. Should you be unconcerned to see the replay, you may of course skip it. The embedded youtube video shows multiplayer gameplay, with a action replay occurring about 40 seconds in. Now, read on to consider the effect of this…

A player who believes he is hiding fully behind a crate or barrel but who in fact has his leg slightly exposed will see in the action replay that he is not fully hidden, and watch his opponent notice, and bring his gun to bear to make the kill. A player who is at great distance but visible will see in the action replay his killer lie down and spend time taking careful aim before making the shot that he would otherwise have assumed was done using an aimbot. A player who is indeed totally hidden behind an object but who gets destroyed by a frag(mentation) grenade will see in the replay that the enemy spotted him sprinting across and hiding a few seconds earlier, so the player did not need to use a wallhack to know he was there. In short, the action replay reassures the player that they were killed fairly.

Finally, I have observed another COD4 feature which helps improve the perception of fairness — the general permeability of most walls and objects in the levels to sustained gunfire. In real life bullets can penetrate many types of materials, and ricochets can kill when taking cover behind much harder objects. This means (in technical terms) that there is only concealment and never cover. The COD4 tutorials and “player challenges” actively encourage players to learn to shoot one another through walls and objects, for instance giving special awards and bonuses to new players once they have made five “through-wall” kills in a row. In many circumstances it is the shortcomings of the physics model of a game which jar the players enjoyment, but crucially most FPS players assume that taking cover behind an object will protect them from all bullets aimed in their direction, which is definitely not the case in real life (maybe this erroneous belief about real-life bullet pyhsics persists because those who discover its falsity do not live to tell the tale). This belief in simplistic bullet physics causes great frustration when people who believe they are cover get hit, be it because of improper concealment, or indeed because of lag, or bugs in the collision detection code for bullets (this does happen). Thus the reintroduction of more realistic bullet and materials physics into games, combined with proper education of the players takes away another major source of frustration for players.

So, top marks to COD4 for their attention to perception of fairness, but I have two more sinister thoughts:

1. If I was a COD4 developer and found myself having to endure regular cheating attempts, and indeed some so subtle that the user could not be instantly banned, I would want the action replay NEVER to show cheating — because as sports stars know, real cheating damages the reputation of a game as much as perceived cheating, if not more. For one, I would smooth the mouse movements of the attacking player, so that even if they were using a top-notch unprovable aimbot, there would be no hint of suspicion in the action replay. So could the perception of fairness techniques used to prevent unwarranted accusations of cheating actually be designed deliberately to cover up real cheating too?

2. Whilst action replay justice might be a breath of fresh air in the computer gaming world, has it really settled controversy and reduced bile in the real-life sporting world or not? Or does the presence of more information and data just undermine the authority of referees and others yet further? Could action replay justice adopters actually be shooting themselves in the foot?

4 thoughts on “Action Replay Justice

  1. On a public level your article is farily valid.

    At a higher skilled competitive level however, when players use comms software such as Ventrilo, or make reflex shots, or little or no cursor movement shots with an aimbot, in a world where even a slight competitve edge can make a world of difference, then your theory holds little sway unfortunately. Also the use of sound in CoD4 is a great aid in wallbanging.

    The kill cam is an interesting concept, but at a higher level provides very little indication of hacking.


  2. Crispin/Blinder–

    Glad you found my article interesting. I’m a bit uncertain what you refer to when you say “your theory holds little sway”, maybe you could elaborate? Do you mean that while the kill cam may assure the average player that someone is not cheating, it does little to reassure a competitive, skilled player, who may be aware of cheating methods which are far more subtle. If so, I certainly agree with you, and I was never trying to argue that the kill cam had much impact on determining the real truth of cheating, just on helping reduce the perception of cheating.

    The name of your website — xraygaming — reminds me again of how much the ability to see enemies through walls dominates the typical player’s perception of the activities done by a cheat. And ironically there are so many other ways to achieve this information gain which do not involve xray vision … voice communication from teammates (alive or dead), behavioural profiling (you study your enemy and can predict where they will be), sound cues (as you point out yourself above)… the list goes on.

    And worst of all, xray vision (or the ability to locate enemies beyond your field of view) is the one class of hack which can be made completely undetectable. I hope to be publishing some results on this blog shortly of my own studies on passive analysis of the packet streams from tactical shooters, to consider what sorts of cheating can be performed whilst being guaranteed undetectable (i.e. not even running on the same PC as the game).

    So what sort of cheat/hack/exploit do you believe is most worried about in the perception of the 1% of gamers who might consider themselves skilled competitive gamers? (this may not be the same as the actual most common cheat used by the 0.1% of gamers who do cheat)


  3. When I say your theory holds little sway, yes I do mean that “detecting” a cheat via kill cam is completely unreliable when it comes to a small percentage of competitive players who may cheat in competitive online tournaments. Although it may stand a (small) chance of showing up “blatent” hackers at a lesser competitive level (public play servers and the like). Regarding “perceptions” of cheating, thats not something I deal with when developing – so I cant comment, although I possibly misinterpreted your article as inferring that the kill cam delivers a useful mechanism for “detecting” cheats.

    I cant really speculate on gamers perceived worries regarding cheats, but its common sense that non public – privately coded cheats stand less chance of being detected by skilled player/cheater and are thus more feared by gamers than your average publically released “hack” – regardless of exploit type/technique

    Lob me a mail if you want to talk about this further offline.

  4. Back in the days when I played CS watched my brother play CS, it was dead players who noticed cheats (provided the server allows first-person views of the opposing team, which might obviously be disabled for Ventrilo reasons).

    There were a lot of accused cheaters, and I vouched for people who were obviously more skilled than cheating. My brother even got banned once.

    And why? Skilled gameplay can be undistinguishable from cheating. My brother started “flick-aiming” (I followed suit) – the logic is that it’s easier to track something when everything else isn’t moving (imagine how much easier it would be if you could aim without turning your “head”) and without compensating for mouse lag [1]. Guess what? It looks like aimbotting.

    I make a few assumptions when looking for cheaters:
    1. Cheaters can’t move (this also makes them easy to kill)
    2. Cheaters don’t have tactics.

    So if a guy kills 8/10 Ts in de_rats (it looks very impressive), he’s probably not cheating. It’s not actually that difficult if you’re good and a little lucky – everyone else is probably dead – and is probably the easier way to come out top. The sitting duck with impressive aim is probably cheating.

    [1] I lament my camera’s lack of a proper viewfinder when I do a high-speed burst at 10x zoom and am completely unable to keep it pointing in the right direction. It’s obvious why: the image processing pipeline is about 0.4s long, and eventually I’m compensating for something I’ve already compensated for. The image stabiliser results in the same sort of effect, and I suspect that it’s non-negligible even at 50 fps (PAL [2]).

    [2] Yes, PAL is 50 FPS – the F that matters, anyway. It’s a pity that most movie players (and, presumably, some encoders) deinterlace into p25 and not p50; motion is obviously more jerky even at 30 fps, and being able to track people move is what it’s all about [3].

    [3] Cops ought to crack down on people with flashing bike lights. I can see you’re there, but I have no idea where you are or where you’re going – it’s like playing a game at 4 fps [4], but with lots of black between each frame. They used to pay people to do this full-time with RADAR blips.

    [4] I was better with the shock rifle at 10 fps (320×240) than I was on a better computer (more like 30) . This contradicts everything I’ve said above, which is puzzling.

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