If there's one benefit to the Steam summer sale, it's that players like myself get to try out a lot of games that they missed out on in the past.  While for most players this might mean the hits from a year or two ago, that can also mean far older titles that this generation may not have experience with or have even played before.

Thief: The Dark Project is one of those games.  Originally released in 1998, and situated right in the middle of the "thinking man's shooter" trend defined by the likes of Half-Life and System Shock 2, Thief was a stealth game that pioneered advancements in AI, physics, graphics technology, and most importantly, was able to make use of its innovative features to introduce gameplay that had never been seen before (or, for the most part, since).

In this article, I'll be taking a look at some of Thief's successes, as well as why its sleek, stealthily efficient design holds up so well even over ten years after its release.

Building Blocks

In my opinion, the strongest games are always those which create systems of rules and interactions that allow players to experiment freely, to see the effects of different actions within those systems in order to come up with solutions to various problems.  While many games these days are created as scripted, linear thrill-rides built to entertain in the most bombastic fashion, Thief comes from, interestingly enough, the same school of thought that has spawned simulation and strategy games - that mode of design thinking that says "pull the player in a bunch of different directions simultaneously, and good gameplay springs forth."

Thief, is, on the surface, an extremely simple game - it's about getting to objectives in one piece by evading enemies.  Where Thief really differentiates itself is in all the different options it provides players, and the ecosystem that they live in.  While some titles will resort to fantastical representations of their mechanics in the form of magic, or sci-fi technology, Thief revolves wholly around two basis senses: sight and hearing, and the player's ability to manage being heard or seen by enemies.

By putting these two resources in conflict with the goal (get to the end of the level), Thief is able to pose incredibly challenging problems to players which are made complicated not by any pretense of depth in RPG-like leveling, or hundreds of weapons to choose from, but by modulating the player's ability to manage resources, through careful level design and enemy placement.

Visibility is the most obvious and most important resource for players to manage. Every enemy has an (invisible) cone of vision, although different enemies are able to see with varying effectiveness.  Being seen in Thief, while not tantamount to failure, is still a major problem and in most cases the player will want to avoid being seen as much as possible.  Vision must be managed in two ways:

1. Light.  Light is everywhere in Thief, which is a big problem when you're trying to remain unseen.  Hiding in shadows is the fundamental action players will perform in Thief, and the vast majority of gameplay challenges revolve around either finding shadow or creating shadow.  The player is able to manipulate light and darkness through items like Water Arrows (to extinguish torches) and Fire Arrows (to light torches) - limitations on the player's quantity of arrows ensure they are indispensable, but precious.  Moreover, some lights can't be extinguished, which means that players, at some point, will always have to expose themselves - which leads to...
2. Movement.  Movement is really where Thief's gameplay earns its complexity.  Control-wise, Thief is extremely simple - it controls identically to first-person shooters, but also includes leaning and the ability to perform two more advanced acrobatics - mantling ledges and climbing ropes.  Movement is in direct contrast with vision - moving makes it easier for enemies to spot the player, and light must typically be avoided while moving.  Moving more slowly offers more safety from direct line of sight, but moving quickly is generally safer when enemies don't have a direct line of sight.

If these two elements were all players had to manage, then gameplay would already be fairly complicated and interesting.  However, Thief also makes sound nearly as, and sometimes just as important as visibility.  Back in 1998, Thief had some of the most realistic sound effects and 3D sound positioning of any game, and like the dynamic lightmaps creating light and shadow, the gameplay took full advantage of this:

1. Movement speed determines how much noise the player makes.  Whereas visibility only matters if enemies have line of sight, sound will alert enemies in a much wider radius.  Alerted enemies aren't just harder to avoid, they're harder to kill or knock out.  Therefore, not only does the player have to manage exposure by moving precisely and carefully, but the sound created while moving as well.  Certain routes in Thief require running to traverse, often due to the more advanced acrobatics required, and balancing sound created vs. the ability to reach a location more quickly becomes a common and compelling risk/reward element throughout the game.
2. The surface the player walks on determines how much noise is made.  Walking on grass and carpet stifles noise and allows the player to move more quickly with more confidence, but tile, metal grating and other noisy floors require extremely slow movement to traverse, and even then there's no guarantee enemies won't perceive something.  Many, many environments take full advantage of this by mixing different types of floor surfaces in complex patterns, again posing a risk/reward dichotomy that often forces the player to pick between direct exposure in bright light vs. a noisy surface with patrolling enemies.

It goes without saying that most of these systems also help the player as well - being able to see enemies is more a privilege than one might expect, and hearing them, including their commentary, the surfaces they're walking on, and their 3D position in the world all provide the player with extremely valuable feedback - and obtaining that information can, in many cases, also put the player at risk, adding yet another layer of risk and reward.

Light and sound, and their relationship to player movement, are enough to make even the smallest of challenges in Thief interesting.  Movement in videogames is usually something we take for granted, and modern games have had different floor surface types, sound effects associated with movement speed, dynamic lights, etc. for years - yet in almost every game, it's entirely cosmetic.  In Thief, it is the game - and in the years since, there hasn't been a single stealth title that's been able to replicate the strength of the design or the implementation.

Putting the Tools to Use

With the basic mechanics out of the way, it's worth going into discussion about the level design.  Thief pioneered an open-ended style of gameplay which was more objective-oriented than the gameplay found in earlier shooters like Doom and Hexen, and drew a lot from System Shock some years before.  Thief's stages consist of sequential series of rooms, almost every one posing different gameplay challenges, which the player has a great degree of freedom in navigating.  Games like Deus Ex: Human Revolution today faithfully recreate the same design of branching paths leading to the same goal.

The strength of Thief's level design can be seen in its very first stage, a theft of a priceless scepter inside Lord Bafford's manor.  Immediately, the game opens with the player staring down the front entrance of the place.  In every other shooter, the obvious choice would be to barge down the front door and fight the guards... but thanks to a warning from the player character Garrett, and a quick death should the player ignore it, game teaches, in its very first challenge, that the frontal assault is not advisable.

 Instead, the player is encouraged to explore the streets around the manor.  Along the way, there are a variety of side paths, including a sewer system which the player can crawl through to gain some early extra valuables and a cache of equipment.  This sewer is by design rather confusing and maze-like, which teaches the player to keep a mental note of landmarks and sets the stage for many of the game's later environments, which eschew hand-holding and offer players multiple routes.  Its optional nature and the reward for exploring it also does a great deal to encourage players to step off the obvious path.

The first enemy the player faces is actually completely impotent - a drunk guardsman who stands in front of a locked door.  This encounter subtly teaches the player that there are a variety of ways in dealing with enemies - in this case, it's possible to either knock the guard out and take his key, kill him, or pick his pocket and sneak in.  As he's no threat, there's no danger of the player making a mistake in the early stages (but that trend in enemy effectiveness will change very quickly).

Once the player gets inside the manor, challenges gradually ramp up.  The first areas are relatively straightforward, and teach the importance of staying out of sight by rooms that emphasize light and shadow, encouraging the player to make use of them.  Shortly after, different floor types are introduced to demonstrate how different surfaces affect the noise both the player and guards make - with the player first observing this in the enemies themselves by hearing their footsteps change, rather than allowing the player to run ahead only to find him or herself in a combat encounter with newly-alerted enemies.

The final challenge of reaching the scepter is actually fairly devious for players concerned with actually being stealthy, but serves as a great final lesson that prepares the player for the rest of the game.  On the top floor of the manor, the floors are decorated with tile, which produces a lot of noise, and a heavily-armored guard patrols.  The tiled surface is broken up by patches of much quieter carpet.  The player's goal, the manor's throne room, is locked, and the key can be obtained either by braving the loud corridors or by taking out the guard.  Once inside the throne room, a similar challenge of carpeted and tiled floors awaits, but this time, the single stationary guard is much harder to avoid.  Crafty players, in both instances, can actually "ghost" the entire upper floor by precisely jumping between patches of carpet.  Either way, navigating the manor to reach the scepter is a rather involved and challenging affair for an introductory stage, but it ensures that players will have fully grasped the game mechanics and now will be ready for greater challenges.

Variable Challenge

The last thing that still makes Thief an excellent game to this day is the way that it handles challenge.  Most games have a set difficulty curve that is designed to fit a median skill level, usually erring on the easier side - I've heard more than once that it's a good idea to "make a game easy, then make it even easier."  Thief does away with this by providing a multi-tiered approach to difficulty levels:

1. Higher difficulties reduce the player's resources.  Rather than give the AI severe handicaps, Thief reinforces the stealth gameplay by making resource management, including both health and items, more important, as there's much less room for slipping up and wasting supplies.
2. New objectives.  Playing on normal won't give you the full Thief experience.  In most missions, actually escaping the level is omitted, with a simple cut to the summary screen occurring once the main objective is complete.  When played above normal, many missions have secondary goals that appear, such as special hidden loot to find, or contacting other characters during the mission.
3. Extra loot.  Players who scour every nook and cranny of the game levels will walk away with more loot, and summarily, more money to spend between missions on more and better gear.  There's greater risk in exploring the whole level, but the cash usually makes it worthwhile.
4. Multiple gameplay options.  The open-ended emergent gameplay of Thief is itself a way of regulating difficulty.  On the normal setting, combat, while challenging, is a viable solution in many cases, ensuring that even if players can't sneak through the level, they can still hack and slash through.  Pure stealth is the hardest approach, of course, and the brilliance of the level design only becomes apparent when playing in the sneakiest way possible.  Most players will stick with a mix of violent and non-violent means as appropriate to each situation, but they are never forced into one or the other.
5. Advanced techniques.  Although many of the game's levels are labyrinthine, most are straightforward to actually get around, and most challenges can be solved by knocking out an enemy, picking his pocket, etc.  Players who spend more time with the game, however, will go to appreciate other aspects of it, like its physics simulation, which allows the player to pick up and throw or drop objects, and the new opportunities they provide for solving problems.  Stacking crates, throwing bottles to distract guards, and more expand the fundamental options available.

The reason Thief still lives years after its release, not counting its extremely dedicated modding community, is that players are still looking for ways to optimize their routes through levels, to complete them more efficiently, and to achieve that vaunted goal of ghosting the entire game on the hardest difficulty.  Most players will never do this, but the game systems are flexible and rewarding enough to not just accommodate, but invite experimentation and replays.

Closing Thoughts

I first played Thief shortly after its release, and I admit, at that age it wasn't quite the game for me.  As I've grown older, I've appreciated the game more and more, and it ranks as one of my favorite titles.  Taking a trip down memory lane today wasn't just nostalgic and fun, but it was highly informative as well, as the strength of the design shines through despite the dated visuals.  For all the great graphics and art direction we have today, Thief is one of the few games that uses every bit of its technology to enable significant new gameplay possibilities.

It's also a shame that, since Thief, there really hasn't been any other game like it.  The sequels in the series have certainly delivered, but developers chose to embrace the action angle of the stealth-action genre in the years following Thief, as well as the more accessible third-person perspective.  Perhaps a little too cerebral and slow-paced for broad audiences, and its contributions to gaming slowly faded over the last 15 years, Thief's unique simulation-style gameplay still remains largely unmatched.