27 April 2014

Assist bundles in Forza 4 and 5

Forza Motorsport 4 is a realistic simulation racing game. If they want to, players can handle the clutch, tire-wear, and other minute racing details. For beginners, the game provides assists that take care of these details automatically. For example, the Braking and Steering assists make turning easier, the Line assist shows the optimal path to follow, and the Transmission assist takes care of switching the gears. For a description of the assists, check these websites.

While I was at Microsoft Research during the Summer of 2013, my mentors and I looked at patterns of progression in FM4. Among the things we published, we found that players rarely used the assist bundles shipped in FM4. FM5 came out in November 2013. This post describes how the FM5 designers used our findings on FM4 to improve the assist bundles.

Assists in FM4 and FM5

Here are the assist bundles shipped in FM4.

Easy Medium Hard Advanced Expert
Steering Assisted Normal Simulation
Stability ON OFF
Traction ON OFF
Brakes Assisted + ABS ABS only OFF
Transmission Automatic Manual Manual + clutch
Trajectory Line Full Braking only OFF
Damage Cosmetic Limited Simulation

Below are the FM4 bundles we suggested, based on player data in Career mode.

Easy Medium Hard Advanced Expert Comments
Steering Assisted Normal Simulation Unchanged
Stability ON OFF Unchanged
Traction ON OFF Unchanged
Brakes Assisted + ABS ABS only OFF ABS-only from Medium onwards
Transmission Automatic Manual Manual + clutch Manual from Hard onwards
Trajectory Line Full Braking only OFF Bumped down: shifted all cells to the left.
Damage Cosmetic Limited Simulation Simulation from Hard onwards

And below are the bundles shipped in FM5.

Easy Medium Hard Pro Veteran Comments
Steering Assisted Normal Simpler: now binary. In Custom bundle, Assisted steering forces Assisted brakes.
Stability ON OFF Bumped up
Traction ON OFF Bumped up
Brakes Assisted + ABS ABS only OFF available in Custom bundle.
Transmission Automatic Manual Bumped up. Clutch available in Custom bundle.
Trajectory Line Full Braking only OFF available in Custom bundle.
Damage Cosmetic Simulation Simpler: now binary.

In short, the bundles in FM5 are easier than their FM4 equivalent because the Stability, Traction, and Transmission assists have been bumped up. Clutch transmission, ABS-OFF, and no trajectory line are only available in a Custom bundle. The FM5 designers did not exactly follow the bundles we suggested. Why is that? See below.

Assist progression

For each race number, we look at how much of the player base still has an assist enabled. The goal is to see how fast players disable an assist. The graph below shows exactly this.

Let's take the Transmission assist as an example. In the first race, the Transmission is automatic for 80% of players (the orange line starts at 0.8), manual without clutch for 15% (the space between the orange and brown lines), and manual with clutch for 5% (the brown line starts at 0.95). Even among the players who reach 100 races (17% of the total player base, cf gray line), only 15% use a manual transmission with clutch. That's why in FM5, manual transmission with clutch is only available in a Custom bundle: very few players use it. Same story for the Trajectory Line-OFF and ABS-OFF assists. In the end, the FM5 designers actually used our findings in their product!

Of course, we need another study to assess whether FM5 players are actually using the default FM5 bundles or not.

A note on Rewind

When you miss a turn, you can press Y to rewind the game and try the turn again. In FM4, the ability to rewind is an assist. Turning the assist OFF grants a 20% credit bonus at the end of a race. In FM5, each rewind costs 1% of the race's credit. I like this change for several reasons:

  • In FM4, I enabled rewind in case I needed it during a race. But I only rewinded every 3-4 races. 20% was a lot of credits missed, though, so it felt a bit frustrating.
  • A fixed price encourages players to rewind as much as they want. So, to get more bang for the buck, they increase the difficulty of the AI opponents, and rewind every time they don't make a perfect turn. This is the same lame trick as saving-and-rerolling in RPGs. Racing this way is excruciating. It also takes longer to complete a race, so the amount of credits gained per hour may actually be lower with more difficult AI.
  • FM5's rewind cost is proportional. This is advantageous for players who rewind rarely, and disadvantageous for those who rewind dozens of times per race.
  • I prefer paying the cost automatically, in the stats screen at the end of a race, rather than manually, through an assist menu before the race.

18 April 2014

Using achievements for analytics, retention, or skill

Achievements can have many purposes in a game.

For analytics

At GDC 2010, Bruce Philips from Microsoft showed how he used Xbox Live achievements to evaluate progression and campaign completion in a dozen FPS. These achievements already existed, and were determined by the game designers, yet provided very useful for analytics.

Traditionally, achievements are binary: you have unlocked it, or you haven't. You can treat achievements as milestones that the player reached. Milestone achievements include: FPS campaign milestones or Forza 4's "import data from Forza 3".

Achievements can also take several levels. For example, Clash of Clans' Release the Beasts achievement takes 4 values: 0 when you start, 1 when you unlock Archer, 2 when you unlock Wall breaker, and 3 when you unlock Dragon. This achievement, by itself, suffices to segment the player base into new, intermediate, advanced, and expert players. It's a double-win: players have more achievements to go for, and you get a better picture than with a binary achievement.

An achievement can keep counting even after it's been unlocked; for example, Clash of Clans' Gold Grab has 3 steps (4 values) but keeps track of the gold you looted. That way, achievements can also be numerical, not just binary or Likert-like.

Achievements can be even more complex and hold metadata such as when you unlocked it, how many days it took you to unlock it, after how many tries, in how much time, and so on. With this metadata, you can label player behavior more precisely. For example, a Clash of Clans player may unlock Gold grab 3 after 3 months where another would only take one month. The later certainly plays much more (number of sessions, session length) than the former.

For retention

Achievements provide long-term goals to the player. Moreover, they can be made so the player always has a near-complete achievement in sight. For example, you reach 490/500 mortars destroyed in Clash of Clans' Mortar Mauler achievement. You play another hour to destroy 10 mortars and get the 10 gems, but by then, another achievement has reached near-completion too, and you could play another hour.

Retention achievements don't always involve grinding. They can encourage the player to explore the design space.

For skill (or luck)

For example, in FTL Repair back to full health with only 1 HP remaining. Skilled players can risk it, for the thrill. But other players can also wait for it to happen by itself.

Other FTL examples include completing a mission in less than X minutes, or not using any weapon until sector 5. Or even taking 5 turns in a row in the card game Ascension.