First off, Fever Knights is a beautifully illustrated RPG that uses the Zweihander(Early Warhammer) engine (d100, Roll-Under). Although it references multiple video games (Final Fantasy, Street Fighter, Dragon Warrior), overall tone for me was Earthbound meets Scot Pilgrim.
Making a character consists of choosing: Identity/Orientation, Zodiac (determines elemental resistances!), Clothing Style, Vibe (First-Impression), Mystical Experience (the reason you can enter this "other" world), Class (typical D&D ones), and Personality.
Class is the most important, so will go into that a bit. Each Class gives you access to unique Fever Modes (think Limit Breaks from JRPGs), Powers (abillities activated for free and without checks), and Techniques (abillities that require a cost and/or checks).
For instance, the Bard can:
Fever Mode: Raise up in the air encircled with light, transform into a Empyrean Emcee, heal all damage, and allow others to Guard for free.
Power: Extend hand and let someone take the stage (Skip turn and let another player take a free one).
Technique: Pay 1 Luck, Summon a keyboard that floats next to an enemy and plays an offkey tune (reduce damage by 1d6).
Progression is fast and easy since it only involves checking a chart and obtaining the next Unlocked Ability. This happens at the end of every session (no EXP points) (twice if playing on Hard-Mode). This includes increasing Stats, raising Defense, and gaining Elemental Resistances. Every 4 Levels or so, a new Technique is learned (chosen out of 9) and every 10 levels you raise to a new Tier (access to stronger Techniques/Powers and unlocks Multiclassing!).
To touch on combat, everyone has 6 levels of health ranging from Unharmed to Fainted. In order to bump someone down the track you need to inflict enough damage to pass their Thresholds. For instance, Rotten Milky's Thresholds are: 5(11/17/23). If you manage to inflict 19 damage, that would be enough to knock it down 3 levels!
Enemies are the highlight of the game for me though. Each one is incredibly unique, quirky, and fun. For instance, Rotten Milky, a small carton that uses its toxic milk to poison.
Finally, the last quarter of the book is devoted to a series of connected adventures that should give a good example of how sessions should go. I imagine this is enough for at least 7 nights of gaming!