[In an in-depth design article originally published in Game Developer magazine, Street Fighter II HD Remix designer Sirlin discusses who's done things right -- and wrong -- when creating save systems for video games.]

I once heard Peter Molyneux say that during the development of Populous he didn't want the player to be able to pause the game. His reasoning was that Populous is a world that goes on with or without the player. Luckily, his friends talked him out of it, pointing out that sometimes the doorbell rings, the phone rings, or the baby cries.

Games are not for game designers and their ivory-tower ideals-games are for players. Players have lives outside of our games and we should respect those lives and design our games accordingly, rather than expect our players to design their lives around us.

Players should be able to save anytime they want, or more precisely, they should be able to stop playing your game anytime without losing their meaningful progress.

This is an old argument where one side talks about the convenience of saving anytime and the other talks about the need to make games challenging, but this is a false dichotomy. We can allow the player to stop playing without excessive penalty and make a challenging game. It's just a matter of defining what "saving" actually means.

As an example, Mario 64 doesn't literally allow the player to save anywhere they want, but it still meets this requirement in spirit. The point of the game is to collect all 120 stars, and every time you collect a star, you "save and continue." You cannot save your exact position in a level, but such a feature isn't needed anyway.

The geography of the game is designed such that a player can reach the entrance to any level in just a few seconds by navigating Mario's castle and getting back to any specific goal in a level doesn't take long either.

This preserves the game's difficulty (players can't save and load to get the stars more easily) and it also means the player can turn the game off at any time, knowing that the only important progress (collecting stars) has been saved.

Save Point, Checkpoint

God of War 1 and 2 and Resident Evil 4 all use the same save system, which is also common in many other games. They all have save points and check points. Save points let players save their progress and load it later. Check points are sprinkled invisibly between save points and if they die, they go back to the last checkpoint rather than all the way back to the last save point.

This system isn't too bad, but it doesn't do a good job of letting the player save and quit at any time, either. It would make more sense if the player could pause the game at any time and save progress up to the last checkpoint.

I'm not suggesting that the player should be able to take a step, save, fire a shot, save-just that he or she should be able to stop playing the game and resume from the last checkpoint. After all, that would happen anyway through dying.

Why separate save points from check points in the first place? I think the answer is for technical reasons rather than design reasons. God of War was designed for the PlayStation 2 and Resident Evil 4 originally appeared on the GameCube (and later on PlayStation 2 and Wii).

These consoles take a few seconds to write a save to the memory card, so doing this every time the designers wanted a checkpoint would probably have been too annoying to the player. This lead to spread out save points and the addition of check points for convenience's sake. In the future, we won't have these technical restrictions.

Gears of War was designed for the Xbox 360, a system capable of writing a save file quickly. Gears of War's save system is a definite improvement over God of War's and Resident Evil's: The player can play through the entire game without having worry about finding save points, but can also quit playing at any time and automatically start at the most recent checkpoint.

Gears of War does this by having many checkpoints, all of which automatically save progress without any action required from the player.

This example well-illustrates the false dichotomy I mentioned earlier. The save system is both very convenient and does not interfere with the difficulty of the game. In fact, Gears of War could be tuned to be arbitrarily difficult without sacrificing any convenience in its save system.

Multiplayer

Save systems get a little trickier in cooperative multiplayer games. Players expect to be able to join a friend's game and leave at any time, and to save and continue their progress later without the game's save system getting in the way. Gears of War does a great job here too, allowing a friend to join an in-progress game at any time (taking over the AI for the character named Dom).

The player can get through a couple of chapters alone, then have a friend join who can leave at any time and pick it up again later. Even if the friend is new to the game, they're still allowed to join someone who's playing the last level, because Gears of War is trying to be as convenient to the player as possible.

One hitch is that when the friend leaves, the player must briefly quit the game then restart it from the same checkpoint. On this matter, Lego Star Wars has Gears of War beat because it allows a friend to seamlessly join or leave a game without ever quitting out to a menu screen.

Playing Gears of War with a friend is easier than playing alone (there are no AI adjustments between coop and single player), but it could have been incredibly difficult had the designers wanted it to be. The save system's flexibility doesn't prohibit difficulty.

That said, if you were really serious as a designer about creating a meaningful leaderboard for single player and co-op play (Gears of War doesn't do this), then you'd need a single player mode where no one can ever join in, and a co-op mode where the two players are set from the start and can never switch out.

This would be highly annoying, so it should only be used as a hardcore leaderboard mode inside a game that also offers a more forgiving system.

Massive Saves

In massively multiplayer online games things get even trickier still. On the plus side, players can log out at almost any moment they want in these games, and their character's progress (such as items or experience points) will be saved.

In World of Warcraft, players can't log out while "in combat," and must wait 20 seconds when they do want to log out, but it's pretty player-friendly overall. There's even a hearthstone that lets players teleport back a city (once per hour) so they can end their play session at almost any time with character progress saved.

What's much harder to save is progress on a quest or in a dungeon. If a group of four friends is halfway through a three-hour dungeon, one could log out, but it's socially unacceptable, and that player won't be able to continue their progress in that dungeon later.

This is a worse problem during raids, where 25 people must coordinate their real-life schedules, and the ability to log off at any time is basically gone.

Blizzard has taken some steps to simulate the kind of save points seen in offline games, though. The Scarlet Monastery dungeon starts in an ante-room with four separate portals leading to four different wings. This allows players to play just one fourth of the total experience, stop, and come back later.

Also, the Mauradon dungeon gives players an item half way through that allows them to teleport back to the half way point, so they can continue their journey later. Blizzard added even more winged dungeons and pseudo-save points half way through dungeons in the recent Burning Crusade expansion.

Players welcomed these changes as they make the game much more convenient, though they still fall somewhat short. A single player game with save points more than an hour apart would be considered lacking, but at least Blizzard is moving in the right direction here. There is opportunity in the MMO genre to be even more friendly to players' real life schedules.

Outliers

Let's return to single player games and look at two unusual examples: Dead Rising (Xbox 360) and Castlevania: Dawn of Sorrow (Nintendo DS). Dead Rising has save points, but no check points.

The open-ended nature of the game makes it very easy to forget to save at all, especially considering that the save points are off the beaten path inside the various bathrooms of the shopping mall where the game takes place.

When players die in Dead Rising, they are given a confusing choice: they can restart from their last save point, losing all character progress since they last saved, or keep their character's progress, but lose all save points.

Yes, you read that right. If a player wants to keep their character's progress since the last save (such as experience points gained and moves learned) then they must restart the entire game from the opening cut-scene.

Even stranger, Dead Rising only allows a single save slot per Xbox 360 profile, per storage device. That means the game is trying its hardest to restrict people into playing the game only the way the designer wants, while still remaining easily defeatable if one makes a new profile or uses another memory card. By "defeatable," I mean this grants users the ability to create two save files, a feature common to almost all games.

The reasoning behind these decisions in Dead Rising was probably to create a very specific experience for the player. They are supposed to care about finding those save points, and care that they are in constant danger from zombies and that if they die, the last save point was a really long time ago so it's going to be a big deal. The world is against the player-as it almost always is in the horror genre-and so the game's difficulty is intentionally very hard.

If the player keeps playing through the game and dying and starting over, they'll start each time with a stronger character and with more knowledge of how to navigate the game correctly and save the various victims from the zombies.

Incidentally, this same save system was used in the game Breath of Fire: Dragon Quarter, which was also by Capcom and is rumored to share some team members with Dead Rising.

I understand why a designer might create a save system like this that reinforces the concepts of the horror genre, but games are not meant to satisfy game designer ideals, they are for players. I was personally annoyed by this system to the point of quitting, because I could not play it the way I wanted.

Dead Rising is an amazing technological showcase and combines the design concepts of a sandbox game (go wherever you want, do whatever you want) with the horror theme of a mall overrun by zombies.

And yet, I'm not allowed even two save slots, I'm bullied into playing the same parts over and over because I feel obligated to restart all the time, and the save points require me to actively seek them out, which means it's very easy to play for an hour or so and forget to save, then die.

That type of save system may work for hardcore players (who border on sadomasochism anyway), but the fictional Little Jimmy from Idaho (the person I often design for) is just going to quit playing out of frustration. I know I did.

On the other hand, Castlevania: Dawn of Sorrow has an unusual save feature that is intended specifically for the player's convenience, rather than for the designer's vision. This game has standard fixed-location save points (with no check points) and it also has a second method of saving called a save marker.

Players can pause the game at any time and create a save marker, and then the game quits to the title screen. When they want to play again, they can either load a game that was saved at a save point or they can resume from their last save marker.

The tricky part is that if they resume play through either method, then the save marker is destroyed. That means if the player is in the middle of a boss fight, they can save, stop playing, play something else, then later resume from the exact moment they saved.

But players cannot reduce the game's difficulty with this feature because it does not give them a second chance of any kind. This is another example where the game can remain very challenging, and yet still allow the player to save and quit at any time.

This same save system was also used by Fire Emblem (Game Boy Advance) except you didn't even need to pause and create a save marker. It was automatically created for you any time you turned the Game Boy off during gameplay.

New Mario, Old Trick

One of the most surprisingly bad save systems of recent times comes from an otherwise wonderful game: New Super Mario Bros. (Nintendo DS). It would have been very natural in this game to allow the player to save at any time on the map screen between levels.

Instead, the player must beat either the castle at the end of a world or the tower halfway through the world in order to save. For example, in World 2 this means beating a minimum of five levels before reaching a save point.

Players can also spend their hard-earned star coins to buy a powerup from various mushroom houses which also lets them save, but they very well might not want to spend their coins.

The need to keep the player at arm's length from the ability to save is conspicuous here given the traditions of the genre (Mario 64 did much better) and doubly-so considering this is a handheld game.

Surely the concern wasn't about keeping the game challenging, because NSMB lavishes the player with extra lives the whole way through.

My girlfriend once asked if she could play Nintendogs on our DS, and I had to explain to her that no, she couldn't, because I just spent almost an hour collecting nine star coins and didn't reach a save point yet so I had to leave the DS in sleep mode until I could save.

I'm not sure which game designer sensibility this restriction on saving serves, or why it would ever be more important than allowing my girlfriend to play with her virtual dog.

NSMB really stands alone here. The most incredible part is that when you beat the game, you unlock the ability to save anytime you want on the map screen!

This proves that no technical limitation made the save system the way it was.

The convenience of saving anytime was deliberately withheld from the player, and given as a reward at the end.

As designers, we can't do this, and must instead put the real lives of our players ahead of our game designery ideals.

Saving for the Player

A save system should allow the player to stop playing at any time, allow the player to pick up where he or she left off with as close to zero replaying as possible, and save as automatically and seamlessly as possible, so the player will not forget to do it.

Saving should be treated as one of the player's natural rights, not an earned privilege or a game mechanic around which to make strategic decisions.

The design space we have to create new games is so unthinkably large that we lose virtually nothing by restricting ourselves to designs with friendly save game systems that don't presume to override the real-life needs of players.

As I have shown, this does not even require a tradeoff with game difficulty; even difficult games can have convenient save systems.

We should always try to design a save system that simply serves its purpose and fades into the background, otherwise we might end up like New Super Mario Bros.-a game with sales of over 10 million units worldwide, and with ten million girlfriends unable to play Nintendogs.