How to design unlocks and skill trees

1 The bottom line

Build unlocks that change how players play, space them across the game, and make players choose. Otherwise progression turns into padding, and power creep wipes out the challenge.

2 Key takeaways

• Make every unlock change how the player plays. A new way to act excites players, while a key or a number does not.
  • The Ori team cut the drill because it only burrowed through thick rock and was not versatile, and the dungeon planned around it became a linear story sequence Chris McEntee, Moon Studios14:26.
• Space new abilities across the whole game. A steady supply keeps players wondering what comes next.
  • The old Zelda formula gave a new item in each dungeon, so Link grew steadily more capable Mark Brown, Game Maker's Toolkit13:52.
• Make earlier choices limit later ones. Players then build a character instead of picking at random each moment.
  • In System Shock 2 you can only use the powers and skills you installed, so players look for the path that fits their build Mark Brown, Game Maker's Toolkit3:00.
• Pair permanent power with something that pushes back. Without a counterweight, the game loses its challenge.
  • Deathloop let players keep infused weapons and slabs forever while enemies stayed the same, and Mark Brown felt nearly invincible after 7 or 8 hours, Mark Brown, Game Maker's Toolkit10:51.
• Gate unlocks behind play that teaches the skills you want. Earning the unlock then proves and builds the player's ability.
  • In Rollerdrome the only way to unlock new levels is to finish bonus challenges that push players to play better Mark Brown, Game Maker's Toolkit8:01.

They're about customising your experience. About rewarding different ways of playing. And about forcing difficult choices.

Mark Brown, Game Maker's Toolkit

2.1 Decide what an unlock is

Fill your unlock list with new powers and cut anything that is a stat bump, a toll or a basic move.

• Fill skill trees with new powers, not tiny stat boosts. Mark Brown, Game Maker's Toolkit4:32 says a few extra percentage points of damage or a couple of health points are not exciting to unlock or to use.
  • A good skill makes the player excited to unlock it, then eager to go into the world and use it.
  • Dishonored's new powers and God of War's new attacks are more desirable than numbers in a spreadsheet.
• Do not lock basic moves behind the tree. Mark Brown, Game Maker's Toolkit4:56 says players expect some mechanics by default, so charging skill points for them feels like being held back.
  • Skill trees should generally avoid mechanics the player should already have.
  • Horizon Zero Dawn hid grabbing enemies from ledges behind an unlock.
  • Mirror's Edge Catalyst locked Faith's leg tuck, which was there from the start in the first Mirror's Edge.
• Prune the tree to a few interesting upgrades. Mark Brown, Game Maker's Toolkit5:34 says weak skills added to make the tree look big dilute the good ones.
  • A tightly pruned bush with a handful of truly interesting upgrades is often the best solution.
  • Path of Exile and Salt and Sanctuary have huge skill forests, which is the opposite approach.

2.2 Pace unlocks so there is always a next one

Run a loop of earn, unlock and try, and space the unlocks so the loop never runs dry.

• Build the loop on growth. Game Maker's Toolkit7:57 reports that Horii loved building up experience, getting stronger and buying new weapons in Wizardry.
  • That loop of fight, earn XP, level up and re-equip became the backbone of Dragon Quest.
• Let each new skill be tested at once. Mark Brown, Game Maker's Toolkit4:41 describes Assassin's Creed Origins as a system that feeds itself.
  • He would unlock an ability, test it on a few camps and missions, and earn experience for the next one.
  • The player is always looking forward to the next ability and wants to try it.
• Give players a long-term unlock to fantasise about. Mark Brown, Game Maker's Toolkit8:04 says players push toward a goal because they imagine the day they can use it.
  • A skill tree works this way, as players look forward to wrecking enemies that were difficult at the start.
• Do not bunch key unlocks together. Mark Brown, Game Maker's Toolkit8:11 notes that Symphony of the Night unlocks ten relics at once with the Bat form.
  • Before that it gives five relics at the start, three after the Jewel of Open, two after the Leap Stone and one after Mist.
  • He says it might have been nice to spread them out more across the game.
• Hold the strongest abilities until late if you build puzzles or challenges around constraints. Mark Brown, Game Maker's Toolkit4:05 says it is really hard to make walls that can hold the player in.
  • Unlock abilities one at a time, and save an instant magnet recall for the end.
  • He compares it to the upgraded gravity gun at the end of Half-Life 2, and notes that Portal introduces its abilities slowly.

2.3 Make players choose

If players can have everything, the only choice is order, so make skills cost something.

• Make players unable to afford every skill. Mark Brown, Game Maker's Toolkit2:55 says that when nearly everything unlocks through normal play, players only decide the order.
  • In Assassin's Creed Origins he could not afford all the skills by the end of the game, so he specialised in the hunter and seer branches.
  • That left Bayek weak in one-on-one combat, so he ran from fights and found new approaches.
  • The result was that Bayek felt personal and the tradeoffs were real.
• Attach a cost to powerful abilities and let it show in the world. Mark Brown, Game Maker's Toolkit0:46 describes Prey's Neuromods.
  • They give alien powers, such as turning into a coffee mug to roll through a door gap.
  • Install too many and the friendly robots aboard Talos I read your DNA as alien and target you.
  • In Deus Ex games some paths are locked by your upgrades, so players must find routes that suit their character Mark Brown, Game Maker's Toolkit3:35.
• Try skills with tradeoffs, links and limited slots. Mark Brown, Game Maker's Toolkit8:48 says trees do not have to be lists of pure bonuses.
  • Skills can carry both advantages and disadvantages, interlink with each other, or be equippable only a handful at a time.

2.4 Push players to try more than one style

Players settle into one style, so your unlocks should not feed it and should give a reason to leave it.

• Do not reward a play style with tools that reinforce it. Mark Brown, Game Maker's Toolkit7:52 says many players pick one style and stay with it to the end credits.
  • Style-specific upgrades create a positive feedback loop that locks them in.
  • Use general skill points, allow respeccing, or give incentives to try other styles.
  • Dishonored players quick load when spotted instead of going violent, while Hades rewards swapping to a new weapon.
• Make switching weapons worthwhile. Mark Brown, Game Maker's Toolkit6:31 says a designer should encourage players to use all the tools at their disposal.
  • In Dead Space 1, after buying four weapons players rarely switched, because money was better spent on ammo and health, upgrades were locked into weapons, and ammo only dropped for guns they held.
  • Dead Space 2 hands out power nodes freely, lets players respec guns to recover nodes, and drops ammo for guns they do not own.
• Remove or rotate the favourite tools. Mark Brown, Game Maker's Toolkit16:15 says losing your tools every loop should force you to find and try new ones.
  • Deathloop's infusion lets players keep their favourites permanently, so he never swapped out Shift.
  • Breath of the Wild's breaking weapons do this forcing without a keep-forever escape.
• Split one character's abilities across several heroes. Mark Brown, Game Maker's Toolkit14:54 says immersive sims let players settle into one style and see only part of the game.
  • Mooncrash splits Morgan into a stealth expert, a repair woman, a heavy weapons tank, a PSI specialist and a Typhon specialist.
  • He used abilities he never touched in Prey and had to find new solutions when his go-to answer was unavailable. With Deathloop's single Colt he hacked turrets for about 30 hours.

2.5 Balance power against challenge

Tune how fast power arrives, and where you can, unlock variety instead of strength.

• Set conversion costs and tap output together. Mark Brown, Game Maker's Toolkit4:17 says that if you know the XP needed to level up and the XP an enemy drops, you know roughly how many kills until the player gets stronger.
  • Speed up or slow down progression by changing either the cost of the conversion or the output of the tap.
• Give permanent power a counterweight. Mark Brown, Game Maker's Toolkit10:51 explains that when the player can make the game easier over time, difficulty starts too hard for their skill, then falls while their skill rises.
  • That leaves only a few runs in the sweet spot.
  • Deathloop's Loop Stress system was too weak to register, while Mooncrash used escalating hazards.
• Unlock variety, not power. Mark Brown, Game Maker's Toolkit5:22 says persistent unlocks can widen what the game offers without raising the player's strength.
  • In Enter the Gungeon, boss currency spent in the hub adds more guns to the random drops, and they are no stronger than early guns.
  • Nuclear Throne unlocks new characters with their own advantages and disadvantages, so none is simply better than the default, Mark Brown, Game Maker's Toolkit6:05.
  • Downwell gives new colour options for collecting a certain number of gems across runs, which have no impact on balance, Mark Brown, Game Maker's Toolkit6:33.
• Carry over a temporary boost instead of a permanent one. Mark Brown, Game Maker's Toolkit8:29 says it gives a leg-up without a lasting change to difficulty.
  • In Into the Breach one levelled-up soldier survives death for your next attempt, but not forever.
  • It also gives an excuse for just one more go.

2.6 Make earning an unlock feel like play

Tie unlocks to skill, to the world and to the player's own growth, and keep the menu out of the way.

• Make currency demand skill. Mark Brown, Game Maker's Toolkit9:13 says Rogue Legacy's Charon takes all unspent gold at the castle door.
  • You must earn a lot in a single run, which proves you can stay alive long enough to do it.
  • In Dead Cells, money is lost on death unless spent at an upgrade station, so you must be good enough to bank it, Mark Brown, Game Maker's Toolkit9:42.
• Tie upgrades to objects the player finds. Mark Brown, Game Maker's Toolkit4:52 says Metro Exodus lets you improve your character only through things you find.
  • Scopes and silencers are ripped off discarded weapons.
  • Skills unlocked with currency in a menu feel more like shopping than scavenging.
• Let players shrink their path through the loop. Mark Brown, Game Maker's Toolkit7:35 says this creates a sense of temporal mastery over a limit that first seems impossible.
  • In Minit a 60-second loop is too short for a Zelda-like adventure at first.
  • By creating start points, finding tools and opening shortcuts you eventually finish the whole game within one minute.
• Send players back to early levels. Mark Brown, Game Maker's Toolkit8:38 says that returning to old Rollerdrome stages to finish challenges shows how far the player has grown.
  • They blitz old high scores where they once barely survived.
  • That makes the shift from prey to predator visible.
• Unlock story so failure still moves the player forward. Mark Brown, Game Maker's Toolkit7:04 says narrative gives the player something to hold onto while failing over and over.
  • In Hades you unlock more about each character every time you respawn, and give found items to hub characters to unlock more story.
• Keep skill menus quick in fast games, or make upgrades automatic. Mark Brown, Game Maker's Toolkit8:10 says menus take players out of the world and can kill pacing in a lightning quick game like Doom.
  • Downwell flashes three upgrade choices between levels so you pick one and go.
  • Red Dead Redemption 2 unlocks Arthur and horse skills automatically as you play.

2.7 Where designers disagree

Pacing and persistence depend on what you want the player to feel.

• Front-loading abilities can work if the game never needs an ability the player lacks. Mark Brown, Game Maker's Toolkit13:52 says Breath of the Wild dumps nearly all its mechanics in the tutorial.
  • You see almost everything in the first couple of hours, and only Revali's Gale adds a new wrinkle.
  • Donkey Kong Bananza mixes both: huge freedom, yet animal transformations handed out across the adventure like classic Zelda's items, Mark Brown, Game Maker's Toolkit20:23.
• Optional upgrades can sit outside the pacing. Mark Brown, Game Maker's Toolkit6:30 says the Charge Beam, Spazer, Plasma Beam, Spring Ball and X-Ray Beam are not needed to finish Super Metroid.
  • Because they can be found at any time, the game is less linear.
  • They feel like genuine secrets that other players might completely miss.
• Slow power accumulation trades purity for meaning. Mark Brown, Game Maker's Toolkit10:40 says random generation and permadeath stop players from leaning on slow power accumulation, so it is all about skill.
  • Slow accumulation adds meaning to each run but brings the backwards difficulty curve and ambiguity over why the player won.
  • He prefers the purity of roguelikes like Spelunky over roguelites like Rogue Legacy.