1. Introduction of the Game
Cooking Fever is an addictive, time-management game that entices players with its engaging cooking and restaurant managing gameplay. Developed by Nordcurrent, this game tests your culinary skills and your ability to work under pressure as you serve hungry customers. Players must keep up with a stream of orders, prepare an assortment of dishes, and work hard to make their restaurant a success.

2. All Characters and Levels of the Game
The characters in Cooking Fever are primarily the customers who come with a variety of food preferences and patience levels, contributing to the diverse challenges players face. The main character is the player-controlled chef. The game boasts an extensive range of levels across various restaurant settings – from fast food and bakery to Chinese and Indian cuisines, each with its progression and difficulty.

3. What Attracts Users Most to the Game
Users are most attracted to Cooking Fever's vibrant graphics, the satisfaction of successfully managing the kitchen under time constraints, and the extensive variety of dishes to prepare. It also offers the joy of growing a simple eatery into a world-class dining destination. The constant updates with new levels and features keep the game fresh and engaging for players.

4. Why It Is Popular
Cooking Fever is popular due to its accessibility, satisfying the gameplay loop, and the ability to make in-the-moment decisions that have immediate outcomes. It taps into the player's desire for progression, achievement, and the rewarding feeling of completing complex orders and upgrading their kitchen appliances and restaurants.

5. When the Game Was Released and How Many Versions Are Currently Available
Cooking Fever was released on August 19, 2014. Since then, the game has been regularly updated with new content and features. While it remains a single title, its various updates and iterations over the years might be considered "versions" that have added new levels and challenges, ensuring that the game remains current and entertaining.

6. The Most Difficult Part of the Game
Players often find the most difficult part of Cooking Fever to be the later stages where the pace quickens, and the variety of orders increases significantly. Juggling multiple orders with different preparation times and customer patience becomes a challenge that requires precise time management and quick reflexes.

7. Strengths and Weaknesses of the Game
The strengths of Cooking Fever lie in its addictive gameplay, diverse cuisines, and the satisfaction of leveling up. However, it is not without weaknesses – some players feel that the game pushes towards in-app purchases for progression in the higher levels, as earning gems can be a slow process, which might limit the experience for those who don't wish to spend real money.

8. What Other Games Have Been Developed by the Same Developer
Nordcurrent is known for a variety of other games, such as "Sniper Arena," an online sniper PvP game, "Happy Cafe," where you run your own cafe, and "Airplane Chefs," a time-management cooking game set on planes. Each offers different themes and mechanics but often centers around the same addictive and engaging gameplay that Nordcurrent has refined over the years.