Combo

Combos, also known as Action Chains  and Hits,are a mechanic that appear in the Sonic the Hedgehog series.

Description
Combos can be defined as a designated a set of actions performed in sequence, usually with strict timing limitations, that yield a significant benefit or advantage to the player, often times providing the player with extra points the larger their combo becomes, alongside other rewards exclusive to that games mechanic.

Sonic Unleashed
In Sonic Unleashed, combos are in appear in both versions of the game during the night stages. They also appear in the day stages, where they are referred to as Action Chains, albeit only in the Wii/PS2 version.

Day
Action Chains can be activated through various means, including destroying enemies, bouncing off of springs, running through dash panels, and jumping through Rainbow and Dash Rings. Depending on how long the player keeps their action chain going, their boost gauge will be filled accordingly.

Night
At night, combos are activated in a manner similar to classic beat-em up video games, wherein the player must make sure to beat up and attack the enemies within a small time frame in order to maintain their combo. Combos are activated and maintained through battling Gaia Minions and Eggman robots.

Alongside doing giving the player the expected score bonus the higher their combo goes, the player is also rewarded via their Unleashed Gauge being increased at a faster rate

Sonic and the Black Knight
In Sonic and the Black Knight, combos, referred to as hits, are activated and maintained through killing Knights of the Underworld.

Alongside giving the player extra points the higher the combo goes, the player will also start to be rewarded with rings if their combo reaching 15 hits or higher with each following hit they land.

Sonic Runners
In Sonic Runners, players can activate and maintain a combo through collecting crystals and collecting rings. As the player's combo rises, they will be granted a bonus score for each following combo they manage to maintain the combo.
 * With a 1-99 combo, the player is given a 1 point bonus.
 * With a 100-149 combo, the player is given a 5 point bonus.
 * With a 150-199 combo, the plater is given a 10 point bonus.
 * With a 200-249 combo, the player is given a 15 point bonus.
 * With a 250-299 combo, the player is given a 20 point bonus.
 * With a 300-399 combo, the player is given a 25 point bonus,
 * With a 400- 999 combo, the player is given a 30 point bonus.
 * With a 1000+ combo, the player is given a 50 point bonus.

The combo bonus item will prevent the player from losing their combo regardless of how long they go without grabbing a ring or crystal or if they get hurt by an enemy or obstacle. In addition, it will double the bonus given to the player; if they player is receieving a 10 point bonus, it will be made into a 20 point bonus. The combo bonus, at level 10, lasts for 10 seconds.

The following buddies affect the player's combo in some shape or form.