Tuesday, 22 October 2013

Luck in games

One of the big questions in game design is the luck factor: should there be any luck in a good game, and if so, how much? There is of course no right or wrong answer here as different people prefer different games. What I'm going to write about today is my take on the different aspects of luck in game design.

Image: Lee Daniel Crocker
A good, classic example of a game without any luck is of course Chess. While the design is solid and has stood the test of time, I'm not myself a big fan of pure skill games like that. They tend to be a bit too serious and dry for me. Rather, I enjoy games with enough luck to keep things interesting, but not too much to take the feeling of control away. Let's take a look of different ways of adding luck to a game.

Dice rolls in action results

When talking about luck in games, most people think about dices. In chess every action has a clearly defined and guaranteed outcome: a piece always kills the opponent's piece in the square it moves to. In Risk, the result of an attack is decided by a dice roll instead. Games that add uncertainty directly to the action results define the probabilities for different outcomes of the action and then roll a dice to decide the actual outcome. Typically, the player has ways to affect the probabilities and decide the desired actions. The decision is based on the possible rewards/penalties of the action as well as the probability of success. 

Including this kind of a luck element may easily take away the feeling of control: it's natural to think that when I have a 75% chance to succeed, it's a guaranteed success and won't fail. When it does fail (which happens every fourth time in this case),  it often feels unfair, especially if it was an important action. On the other hand, such an uncertainty can add a lot of tension to the game as one can never be sure of the outcome. As such dice is best used for actions that are repeated many times to even out the dice rolls. It is a dangerous approach to be used for major actions that can change the course of the game.


Another way to add uncertainty to actions is to add a dexterity element into the game. Examples of such games include Angry_birds, Jenga, Pool, BowlingDarts and sports in general. Truthfully the accuracy element in this kind of games is directly dependent on the player's skill and thus the word luck does not describe it well. Still, when we compare Chess to the games listed above we notice an interesting difference: Chess is all about strategy and a huge decision space, where one needs to be able to outhink the opponent. Once the move has been decided, the execution will always succeed. In bowling the strategy is very simple: always knock out all the pins. It's the execution part that makes the challenge as even the best players are not able to do that consistently with every throw.

Adding an accuracy element to a game can make otherwise very simple game more interesting and challenging. A good example of using accuracy as a minor element in a game is HellFire. Both HellFire and its predecessor Rage of Bahamut are essentially sophisticated card collection systems with very simple game mechanics. In Rage of Bahamut, battles are decided almost directly by the card stats, while in HellFire the opponents employ weak points to which the attacks should be aimed at by swiping the touch screen. This adds an interesting accuracy element to the battles as skilled swipes give an advantage over poor ones.

Complex action chains

A slightly different approach to accuracy is found from the attacks in Clash of Clans. The game is essentially a multiplayer tower defence game, where players build their villages and decide the defensive tower setup. Then other players use their army to attack the villages and try to steal resources and points. An army may contain over 200 troops. While placing a single troop is simply a tap on the screen, deciding the order, timing and placement of the whole army offers almost endless possibilities.

After being placed onto the field, each soldier automatically attacks based on its behavior model which is defined by its type. The behavior is predictable and thus in theory there is no luck involved, except traps and invisible towers which are hidden information and thus not completely predictable. But even without those, the sheer complexity of the setup means that it's not possible to exactly predict what will happen. It's a common thing to see my troops go to a completely different direction than I predicted and then get slaughtered by a tower they should have destroyed earlier. This unpredictability keeps the attacks interesting as there is always the chance of failure. Yet,  the failure does not feel unfair as the result was not due to an unlucky dice roll but rather the decisions I made.

The challenge in complex action chains is in the execution part similarly to the accuracy element. The difference is, accuracy uses independent actions which should all be executed perfectly. In complex action chains, the actions are are simpler by themselves, but not independent and the goal is to execute the whole action chain flawlessly.

Hidden information

Many people have asked me why do we keep the opponents hand units hidden in Permia - Duels. Wouldn't it be better if all the information was always available to both players, like in Chess? As you might guess, my answer to the guestions is no. But why is that? What do we gain by hiding the information and adding a luck element to the game through that?

Opponent's hand is hidden during a match

In games like Chess, where all information is always available, the only limitation when deciding the strategy is the computational capability of the player's brains. This makes the decision base huge and easily leads to an "analysis paralysis", which means that the players can analyze a single move for ages if the time is not limited. Of course we can limit the time, but again, it becomes a task of analyzing as much of the available information in the given time as possible. For me this kind of games often feel dry and exhausting to play as there are no real surprises, only raw calculations and memorizing chains of moves.

Hiding opponent's units takes away some of the strategic depth and puts more weight on the tactical side. One cannot calculate the exact strategy for the whole game at the beginning as all the information is not available. Rather, the decisions must be based on the own units and their strenghts and one needs to be able to adapt when something unexpected happens. This drastically reduces the decision base at the start of the game and makes the game feel lighter. Additionally waiting for an opponent's moves is more exciting due to the uncertainty: "does he have the unit which wrecks my cunning plan or not?" Rather than knowing all in the beginning, one needs to try to deduce the opponent's hand during the game based on the units he has already played. This adds the possibility for bluffing, which is another element not possible in a full information game. Simply put: for me, games that have hidden information tend to be more fun to play.

Limited options

Another way to reduce the decision base of a game is to limit the options the player has available at once. Good examples are most card games, where the player's hand decides the available actions while the deck defines the whole actions pool. The player typically knows what to expect from the deck and thus has a vision of the grand strategy, but the decisions which cards to use are tactical ones: How to make the best use of the cards in hand, which might or might not be the optimal ones for the situation at hand.

Limiting the options is often used together with information hiding, which allows even more interesting bluffing elements. Limiting the player's options is also an excellent way to make game sessions feel different as the actions available in different phases of the game vary from session to session even if the whole action pool stays constant.

Varied setup

Varying the game setup can also be used for making different playing sessions feel different and to keep the game interesting for a long time. Instead of limiting the options available, the gameboard or gameworld behaves differently from session to another. A good example is Bejeweled, which always generates a different playing field for the game. Varied setup also reduces the advantage gained from memorizing certain chains of moves, as different situations require new solutions.

In Permia - Duels, the varying gameboard is one of the key elements of the game. Differently positioned landscapes form a new challenge for each game session and require the players to their update strategies accordingly.

 Jani Rönkkönen / Lead designer of Seepia Games.

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