"No reason to play again": add replay value with star ratings, par times and three more mastery goals

A level that ends on a plain “Level complete” gives players nothing to come back for. They finished, and that’s it. Players replay when they can see that they could do better, and by how much. Angry Birds rates every stage out of three stars, and as Wired’s Jonathan Liu put it, “going for the maximum number of stars certainly adds a lot of replay value” (Wikipedia).

All five demos use the same tiny level: the runner moves right on its own, past a crate, a spike pit and a two-block brick wall, to a flag. Hitting an obstacle stops you, so your time depends on how cleanly you jump. A clean run takes 3.11 s. The demo run hits the wall once and finishes in 3.70 s, on both sides. The left ends on “Level complete”; the right adds one trick. Play it yourself lets you jump with a tap, a click, Space or ↑ (hold for a higher jump), and your input drives both sides at once. Your best time and your ghost are saved in your browser, so the last three tricks use your real runs.

1. Star rating

Give 1 to 3 stars: one for finishing, two for a solid run, three for a near-best one. Use one or two measures, set the thresholds from your own play, and show what the missing star needs. In our demo the run gets 2 of 3 stars, and the empty star tells you the bar: “3 stars: under 3.30 s · this run: 3.70 s”. The left side finished the same run and got no number at all.

2. Par time

Show a designer’s target time before the level and next to the player’s result after it. Doom shows par on the intermission screen next to your time, which “allows the player to gauge their skill”; John Romero set the original par times from his fastest run, rounded, plus 30 seconds (Doom Wiki). In our demo, par is 3.50 s, shown before the start and beside the clock, which turns red once you’re over. The run ends “+0.20 s over par”: close enough to feel beatable.

3. Personal best

Save the best result for each level and show it: on the level select, during the run and on the end screen. When it’s beaten, say by how much and keep the old value on screen for a moment, so the player sees the step they made. Mario Kart’s Time Trials save ghost data so players can race “against their own best times” (Super Mario Wiki). In our demo, “Best 4.28” shows during the run, and at the end: “New best! −0.58 s”, with 4.28 struck through as it fades.

4. Next target

Always show one goal just above the player’s current best (the next star, or par) and the gap to it. A specific, close goal pulls harder than “do your best”. In Locke and Latham’s goal-setting research, “difficult specific goals lead to significantly higher performance than easy goals” and than “do your best” goals (Wikipedia). In our demo, the right side shows “Goal: under 3.30” during the run and ends with “0.40 s to your next goal” and a bar showing the gap.

5. Ghost run

Play back the player’s best run as a see-through copy while they play, so they can see where they lose time. In Mario Kart a ghost is “the recording of a player’s driving performance”, and staff ghosts, recorded by Nintendo staff, give a baseline time to beat (Super Mario Wiki). In our demo the ghost is the 3.11 s clean run. It pulls ahead at the brick wall, and the end screen points there: “−0.59 s here”. Now you know which jump to practise. When you play, the ghost starts as that clean run, labelled “DEV”, until you set a best of your own.

Keep the goals reachable

A goal nobody can reach is worse than no goal. Rules for tuning:

• Three stars must be reachable on a clean run. Set the thresholds and par from your own runs, then check that you, or a bot, can hit them. In our demo, three stars (under 3.30 s) and par (3.50 s) both come from the 3.11 s clean run.
• Pick one or two measures, like time or moves taken. Five scores at once and the player can’t tell what to improve.
• Keep the next target close. “0.40 s to go” invites one more try; “12 s to go” says this isn’t for you. And while players are still learning the basics, a learning goal can work better than a hard number; the goal-setting research notes this for complex tasks.
• Count replays. Let testers play the same few levels with the tricks off and on, and stop whenever they like. Voluntary replays, and replays that beat the personal best, should both go up.

Mastery goals reward getting better at one level. For rewards that grow across the whole game, see XP curve formulas.

Add it to your game

1. Copy the skill at the end of this page into your project.
2. Ask your agent: “There’s no reason to replay my levels. Add mastery goals.”
3. Play it, then tune in plain words: “Three stars is too hard on level 4.”

Art and sound in the demos: Pixel Platformer, Kenney Future and Digital Audio by Kenney (CC0).