Based on the review, below are the key features and mechanics of the online slot game, Captain Payback 2:

- Signature superhero theme: Experience the thrilling return of the legendary hero, Captain Payback. The game offers a storyline where the hero tackles threatening technological threats to save the city from an evil scientist and his minion. This narrative deeply immerses players in the gameplay.

- Unique reel configuration: The game adopts a slightly unconventional layout with a 3-4-4-4-4-3 reel matrix that enhances gameplay and can potentially boost winnings.

- Multiple paylines: Offering a generous 75 paylines, players have multiple opportunities to make winning combinations. This greatly increases their chances to achieve significant earnings in the game.

- Special features:

- Scatter Bucks: This feature can help players to fetch more earnings whenever they spin the reels. It brings exceptional potential for winnings and builds intrigue with every round.

- Stacked Wilds: These symbols can stack up on each other on a reel and increase chances for bigger wins. They can also replace any other symbol to complete a winning combination.

- Expanding Wilds: An exciting mechanic that extends wild symbols to occupy larger sections of the reels. This potentially creates more lucrative winning combinations.

- Heroic embellishments: To enhance the storyline and improve user experience, the game is equipped with special effects, such as the hero's signal that shines high in the sky. The details in the game environment contribute to the overall immersion of the player.

- Engaging storyline: Keeping the player's interest is key. The game progresses with the escalating conflicts presented by the nefarious scientist's technological threats and his destructive assistant.

- Lightning strengthened superpowers: Keeping true to the superhero theme, Captain Payback wields his superpowers to combat the persistent evil. This aspect brings an extra level of engagement to the game.

All in all, Captain Payback 2 offers a thrilling gameplay experience for players seeking a blend of robust slot game mechanisms and capticating storyline.