The best games are a slow steady learning process.

They teach and guide while they entertain and challenge. They push players to improve steadily — to master a mechanic not by forcing you to scale a metaphorical wall, but by compelling you to climb a series of metaphorical steps.

This does not necessarily mean they have great tutorials — indeed, many games with awesome learning curves throw you straight into the experience proper. Nor does it mean that they have to dumb down their design. It's simply a matter of crafting progression systems that allow the player to get a handle on the fundamentals early and then to grow and improve at every stage after that.

It's not easy to pull this off. To give you some guidance as to how you can execute a brilliant learning curve, we asked several designers to tell us what games they think do it well.

None of the seven examples that follow are easy games, but all of them meter their difficulty with a well-considered learning curve.

1) Portal: The entire game as a tutorial for itself

From the moment the player wakes up in protagonist Chell's minimalist living quarters, Portal gently prods her forward. As Global Game Jam co-founder and Rochester Institute of Technology assistant professor Ian Schreiber notes, "the entire game is basically a tutorial on how to beat it, except it expertly frames the learning as gameplay." Portal challenges by crafting puzzles around new mechanics and new applications of existing mechanics.

It allows all the time players need to get comfortable with the controls or to think about how to solve the next puzzle, and it scales the difficulty by simply incrementing the complexity.

What you learn in completing one puzzle is needed to figure out the next one, and you have environmental cues that indicate what you need to learn or do (though not how to do it). Some cues are subtle such as the position of sentry turrets, while others are obviously instructional like the warning signs at the entrance to each test chamber. And thanks to these cues there's a clear progression from using portals to walk through a wall to using them for high-speed platforming.

TAKEAWAY: You can simultaneously teach and challenge players at the same time if you weave the learning experience into the environment and level design.

2) Burnout 3: Takedown: Faster cars and tougher challenges matched against improved mastery

All of the Burnout games do a fine job of introducing faster cars and tougher races and challenges at a comfortable pace. But one deserves special praise.

"I absolutely loved Burnout 3," says Corey Davis, design director at Rocket League developer Psyonix. "The pace of acquiring more powerful cars lined up really well with my mastery of the boost system, crashing opponents, and track knowledge."

Each new car is just the right amount faster and stronger than the previous one to maintain an even challenge level and not pull the player out of their depth. The crafted tracks and frantic high-speed tussles with rival racers grow more intense as the player progresses, and there's a rewarding and fun experience for anyone to find — veteran racing junkies, casual fans, and newcomers alike.

TAKEAWAY: You need to constantly test players and push them to execute tougher maneuvers as they improve their mastery of the core mechanics, but there's a fine line to straddle here if you want to keep both inexperienced and experienced players engaged from start to finish.

3) Guitar Hero's multi-tiered difficulty and feedback mechanisms help players learn at their own pace

Much like a real instrument, Guitar Hero offers an intensely satisfying learning curve. It arguably even outdoes a real guitar in this respect, as it provides more useful feedback and gave the player ways to play along to their favorite songs regardless of skill level — the chosen difficulty level affects the number of notes to play and fret buttons to hit. It also adds an extra layer of progression by dividing songs into a "setlist" of increasing difficulty — so the challenge ramps up song by song as well as by difficulty level.

Davis praises this design decision. "I never felt like it was cheap; it felt purely like I needed to get better," he says. And the feedback loops both on the screen during play and intrinsic to the challenge of mastering the twin difficulty systems combine beautifully with the simple joy of making music — of mastering hit rock songs.

TAKEAWAY: Multi-tiered learning curves can let players control their own challenge level and rate of progress, and also provide a clearer indication of how much harder the next stage will be.

4) Dark Souls' difficulty escalates smoothly, and fairly

To someone who's heard about but not played the infamously-difficult Dark Souls, it may seem like a strange inclusion in this list. But extreme challenge and a good learning curve are not mutually exclusive. "The difficulty escalates very nicely," says Red Hook Studios creative director Chris Bourassa.

"Just as you start feeling overwhelmed, you find yourself back in Firelink Shrine," he continues. "It's a clever use of the town hub as a thematic downbeat, and works like a chapter break in the game. As you catch your breath, you can look forward to a meaty jump in difficulty as you set off to the next area, followed by another smooth curve."

Cthulhu Saves the World designer Robert Boyd made a similar point in his 2012 analysis of Dark Souls' design

TAKEAWAY: High difficulty does not necessarily equate to a too-steep learning curve, as Dark Souls exemplifies.

5) Warhammer 40,000: Dawn of War 2: Positive feedback loops inspire confidence to explore the edges of the strategic possibility space

Bourassa also praises the learning curve of real-time strategy/action-RPG hybrid Warhammer 40,000: Dawn of War II. Specifically, he was drawn in by its tension between threat and empowerment. It gives the player confidence to try things and to experiment with new combinations of strategies thanks to a steady trickle of loot and new units. "I always felt confident heading into the missions," says Bourassa, "even when that confidence was misplaced."

The smaller-scale structure of Dawn of War II's campaign missions in comparison to traditional RTS games helps, too. Short missions with small groups of units battling other small groups (and little or no base building) reduce the need to master micro-management and instead allow the player to learn and adapt as the situation demands. The skirmish multiplayer mode doesn't share this well-balanced learning curve, though, as it's too different to the campaign for knowledge transfer and new players tend to get annihilated.

TAKEAWAY: A good learning curve balances danger or challenge with player empowerment; it gives the player a taste of both failure and victory and makes either feel like a learning experience.

6) Ironcast's complexity emerges as depth and layers within the core mechanics

Ironcast is the rare genre-mashup game that gets the blended elements to fit together. It's a Puzzle Quest-inspired tile-matching puzzler with a touch of roguelite adventuring and steampunk-themed resource management and mech-bot warfare.

Bourassa notes that while it looks straightforward at first, it's actually a deeply layered experience. "They do a lot of interesting things with the mechanics at all levels," he says, "and I found the meta-game quite engaging."

The player gathers resources from the tile-matching mode, which they soon learn how to use to engage in full-on turn-based mech combat that involves a range of abilities and strategic and tactical decisions. If they lose a battle, it's game over, but certain upgrades and unlocked mech pilots remain so that they can still feel a sense of progress. All the game's complexity is metered out in such a way that you have time to get comfortable with new mechanics before your skill with them is tested. And the upgrades enable new strategies rather than simply incrementing the power of your weapons and shields.

TAKEAWAY: You can ease players into complexity and surprise them at the same time by starting simple then repeatedly upping the stakes and stripping back the layers underlying the gameplay systems.

7) Super Mario Bros teaches and begins to explore the fundamentals in its first level

The original Super Mario Bros remains a masterclass in game design, and a big part of that is the expert manner in which its difficulty ebbs and flows — a small spike at the beginning followed by a gentle upward curve that has additional spikes at the end of each of its eight worlds (as Mario nears and then battles the world boss).

It's also a great example of how to teach a player without tutorials. "It introduced most of the core concepts in World 1-1," says Schreiber. It didn't explicitly explain anything, but rather left the player to explore and discover the mechanics simply by trying things.

You may not go into the game knowing that enemies die when you jump on their heads and that blocks with question marks on them give coins or items (or what those items do), but you can stumble on these concepts within seconds and extend your understanding of how they work over the duration of the game.

TAKEAWAY: Classic games still hold great lessons in game design, and Super Mario Bros in particular is a shining example of how to quickly introduce the core concepts and then playfully explore their permutations over the rest of the game.

TEACH, DON'T LECTURE

There's no point developing a great game mechanic if only a tiny percentage of players can figure out how to use it. If you're striving for challenge, be fair, and remember to allow players some time to acclimatize to their new-found skills. You need to both give your player the appropriate tools and teach them how to use these tools before you ask them to scale a cliff or make a seemingly-impossible leap.

If you're not trying to make a difficult game, remember that great learning curves should have small spikes along the way to challenge players and test their mastery of the mechanics or to introduce new mechanics.

Most importantly, consider that teaching people how to play your game is not just a matter of telling them what to do and then leaving them alone. Nor is it about micro-managing their experience. You need to let them play and experiment and to ensure that when they fail they can understand why. Mistakes and successes alike should improve their mental models of how your systems work. And they should drive your players to get better at your game, not to walk away.

Thanks to Corey Davis, Chris Bourassa, and Ian Schreiber for their help with putting this article together.