Criminal Case by Pretty Simple Games is one of the best Facebook games in terms of growth. What makes it even more impressive is the fact that Pretty Simple hadn't any hit titles to drive the traffic from. Not to mention the incredibly tough competition within the category of hidden games. 

The amazing growth of Criminal Case is due to several factors but in this post I'm going to concentrate mainly on the game mechanics. Thus I won't be saying anything about the great graphics, smooth gameplay and intriguing level design of Criminal Case. Instead I'll deconstruct the core loop and take you through the great retention, virality and monetization mechanics of the game. 

In the end I'll also try to answer whether Criminal Case has the potential to see the same growth on mobile that it saw on Facebook.

the Core Loop

Criminal Case has the core loop typical for most energy-based game economies. The goal of each session is to earn Stars, which are used to progress in the game. A Star is earned by completing a set of hidden object games. Each hidden object game (HOG) consumes Energy. In other words, Energy is always converted into Stars. The skill element comes from speed - the faster player completes HOG the less Energy they'll end up consuming earning Stars. 

Criminal Case's core loop is traditional for games with Energy mechanics.

Completing levels consumes Energy and rewards Stars. Stars are then

consumed to progress in the game. When player runs out of Energy they

can either wait for it to refill,  ask friends or purchase refill.

Progress follows every session as players can't fail a level due to hint-mechanics. The ensured progressions with every Energy spent is also something typical for Energy based games. Inability to fail can be also seen as guaranteed progressions, which leaves player feeling accomplished after each session.

the Retention 

From game mechanics perspective the retention of Criminal Case is driven by Energy and timer mechanics, which are both boosted by the virality mechanics Facebook provides. From the players' perspective the motivation to return to the game is driven by competition and the need to solve an ongoing case.

Energy 

Solving a case means a several play sessions of hidden object games. Each session is 5,5 HOGs 

(hidden object games)

due to a smart 

design of Energy meter where maximum Energy is 110 points and each HOG consumes 20 points. So by the end of a session player needs 'only' 10 more points they can 'easily' request from friends.

Clearing levels earns points, which are converted into Stars

Stars earned from completing levels are consumed to progress in the game

Timer Mechanics

Player progression is slowed down regularly by timer mechanics, which are designed in form of forensic investigations. These timers are activated usually when player reaches a breakthrough point in the game, halting the progression and encouraging player to pay in order to speed up the investigation.

Timer mechanics are fitted beautifully into Criminal Case

as they are used when player engages in forensics

Story 

The developers behind Criminal Case are without a doubt big fans of the CSI-series. Every case is like an episode driven by a easy-to-follow dialog, plot twists, forensic investigations and dozens of crime scene investigations. 

Players' need to complete is beautifully encouraged by a progress meter, which gets periodically filled up every time player earns and consumes stars.

Every time player consumes a Star the meter shows how close

the case is to being solved

Competition

Key element of a social game is to allow players to playe with each other - or at least create an illusion that they are playing with their friends. Social element is vital as it allows players to collaborate with each other and leads to competition as players start comparing their progress. 

Criminal Case uses two powerful tools to create competition between players: persistent progress map and leaderboards. 

The 

persistent map, which shows how far each player has gotten encourages players to continue playing in order to catch their friends'. What's best about the map progress view is the fact that even though player hasn't been playing the game for months they are still visible to their playing friends and thus act as targets. "If my friend is at level 10, I'm sure going to pass her". 

Persistent map is a great way to create competition even

between active and churned players

While the persistent map offers long-term goals the level based leaderboards are perfect to boost competition for every session and every HOG. 

Level specific leaderboards are perfect to encourage

competition for every session

Replayability

Level design is a huge bottle neck in hidden object games. To counter this problem Criminal Case has players playing the same levels over and over again with a cleaver Star system. 

Stars enable players to progress in the game. The only way to earn a Star though is to play one specific level till enough points have been reached. Player earns more points by completing levels faster. Because speed is rewarded, familiar levels become more productive, which encourages players to play same levels over and over again. 

Virality

Criminal Case has some of the nicest integrated social features on the platform. In fact I believe that together with the great retention mechanics they are the reason for topping the competition. What makes the social elements of Criminal Case so powerful is the natural way they're integrated into the game. On a platform troubled with over-aggressive virality Criminal Case is a benchmark for how to do it right.

Collaboration

Before each HOG start, player has the opportunity to choose a friend as an investigation partner for the round. The reason to choose a f

riend is that they give players up to 4 hints. What makes this feature great is that players who play more actively become more valuable as they have more 'Hints' they can give. 

From players perspective being active makes sense as they are chosen more often as partners and thus have the opportunity to receive thank you gifts (cards that can be converted into an Energy pack). Each Partner can be only chosen once per day, which drives players to play daily.

Friends are shown as Partners who'll offer 'Hints' during gameplay.

Active players offer more hints and are thus more likely to get selected.

After each HOG player can send a thank you gift (Card) to helping Partner.

Requesting

While Criminal Case sports some of the nicest virality features on Facebook it also uses the traditional "spam virality" with mass Energy requesting and sending of daily free energy gifts.

When players run out of Energy they are led

to request it from the whole friend graph. Awful...

First session of the day starts with a popup

prompting player to send Energy to playing friends.

Monetization

With well over 6 million active daily users even a low conversion rate and modest average purchase per player will create massive revenues. 

Criminal Case sports

 three main sources of monetization in: Energy, Pay Walls and Boosters. 

Energy

The Energy reload time is surprisingly slow in Criminal Case allowing only two to three comfortable sessions per day. Restricting Energy supply drives demand till certain point after which it turns into diminishing retention as the sessions are too far away from each other. 

In my opinion the Energy mechanics is very nicely integrated in Criminal Case. It allows those few good sessions a day and leaves players just a step away from another round by the end of each sessions. There's also a nice balance between too many and too few sessions a day.

Pay Walls

After good week of active gameplay Criminal Case slaps players with a pay wall, which probably the main source of revenue in Criminal Case. Players can pass the wall by either paying or requesting help from their friends. 

The timing of the first wall is perfect as at that point of the game players are already hooked to the game and most likely will drop a couple of dollars to keep enjoying it. At least they'll bug their friends for help. 

After a week of game play the progress is halted by pay wall

Boosters

Players can aid their battle for the top position of level leaderboards by purchasing consumable boosters with in-game currency. In game currency is earned by completing HOGs and it can also be bought with real currency. Personally I doubt that the selling of in-game currency is a relevant source of revenue in Criminal Case even though leaderboards are a great way to create demand for boosters. 

Each level has level leaderboard. Boosters help to beat friends

and get your name on top of the list.

Boosters are sold with in-game currency before starting a level.

Chained by its Elements of Success

Criminal Case is without a doubt the best hidden object game I've ever played. Storyline, graphics and overall smoothness of gameplay are beautifully combined with the well though retention and virality mechanics, which have propelled the title into an amazing growth. 

Yet the big question is how Criminal Case will do on mobile. 

In my opinion the biggest stepping stones for success on mobile are ironically the same ones that made Criminal Case a success story on Facebook:

• The beautiful and detailed crime scene, which looks awesome in full screen mode on a laptop, is simply too small when viewed on iPhone's 4 inch screen. 
• While on Facebook players are content with two to three sessions played around office hours, an active player on mobile likes to get 8 and more sessions spread around the day.
• Completing levels is all about speed in Criminal Case. Yet on mobile, where sessions are often interrupted, the turn based model has emerged as the dominant one. For example King seldom uses timers preferring to count turn instead.
• Lack of turns and inability for player to fail a level takes away the most dominant monetization mechanic, which is pay-to-continue (check out my posts on Puzzle & Dragons and Candy Crush Saga for breakdown of the pay-to-continue mechanic). 

My honest opinion? Criminal Case is an amazing Facebook game but I doubt that it will convert into a smash hit on mobile. Though with all their experience, I'm positive that Pretty Simple can create a brand new hidden object game, which is more suitable for mobile.