[In this in-depth article, originally printed in Game Developer magazine earlier this year, Microsoft Game Studios user research expert Phillips looks at a simple but vital problem - why people stop playing games, and what feedback we can give them to encourage them to continue.]

Most games are challenging by design. Winning every time isn't fun, but neither is always losing. The typical user experience is somewhere between these two, with most players experiencing some degree of failure. Players will lose races, blow up, fall to their deaths, get lost, or fail in thousands of different ways. Some will persevere and continue to play, while others will get discouraged and give up.

As we game developers seek to expand our audiences, some traditional methods of keeping players engaged are becoming less effective (according to Microsoft's databanks, which I use as the main source throughout this article). Fortunately, we can do some relatively simple things to motivate players.

Keeping players motivated is difficult. The most popular solution is to manipulate the game's difficulty using tutorials, dynamic difficulty adjustment, player-selected difficulty settings, feedback systems, userfriendly controls, and in-game hints. The goal is to strike the right balance between difficulty and player ability, thereby always keeping the player within arm's reach of a new achievement.

Despite these attempts to balance difficulty for a wide range of people, the players will still experience failure. More importantly, many of these folks will stop playing because of these failures. It's rare for people to leave a restaurant because they don't like the food, and it's not too common for people to walk out of a movie because it's bad -- but game players do put down the controller and leave the game all the time. What's worse, when game players have a negative experience, they are likely to tell their friends, family, and community.

When someone quits a game prematurely, we haven't just lost a player; we've created a detractor.

Quitter Talk

How serious an issue is quitting? It's worse than you might have guessed.

Table 1. The percent completion is found by dividing each player's Gamerscore by the total possible Gamerscore for the title; those numbers are then averaged.

Table 1 shows the average Gamerscore completion for each of the top 13 Xbox Live games for 2008. The data was drawn from about 14,000 players. As you can see, even the games with the highest achievement completion rates (Fable II and Call of Duty 4) had players who, on average, attained less than half the possible Gamerscore.

This particular sample tends to be more hardcore than the average player, and I would expect the actual completion rates for the entire population to be lower than the numbers recorded here.

Of course, the Gamerscore tells only part of the story. Players could finish a game and do little else, resulting in a low Gamerscore but high completion rates. However, most games award achievement points for completing the single-player campaign.

Table 2. The bar graphs show how many players earned a campaign completion achievement -- in other words, finished the game -- for the titles listed.

Table 2 shows how many players finished a sample of the games listed in Table 1 as determined by whether they earned a campaign completion achievement (on any difficulty). For even the most popular games on Xbox Live last year, about 30 percent of players didn't play to the end.

Players don't finish games for many reasons, but no matter what explanations arise, it's also likely that a significant number of players stopped out of frustration and that is what we will discuss here.

What leads some people to persevere after experiencing failure and others to give up? Why do some people anticipate eventual success where others only see continued failure?

There are probably many answers to that question, some of which are out of the game designer's control. However, there are at least two things we can and should do. The first has to do with how we word feedback to players, and the second is related to the goals we provide.