Neon Chrome's Arena mode is a bit unbalanced as to the effectiveness of some classes' unique abilities, and the turret placement and boss appearances can awkwardly take the wind out of the sails. It is also probably a bit formulaic for most people's liking. That said, it's a harrowing experience, focusing very well on skill rather than tricks or abilities. It's a worthy mode that can be entertaining for hours on end.
Rocketbirds 2 suffers from hit-or-miss presentation, with nice rock music in the background occasionally, but an awkward intro. The humour is insipid, focusing on 'funny voices' and tropes. The combat, while getting the basics of weapon types right, never amounts to more than 'shoot and dodge,' and dodging doesn't involve skill or focus. A dearth of enemies and banal platforming focusing solely on enemy manipulation to open doors and such doesn't help. This mediocre game won't entertain the pros, but serves as an okay intro to twin-stick shooters.
Even with their linear nature, the gameplay of these games is the high point in the series, offering loads of customizability and the ability to plan out the next move. Use your own strengths or reduce weaknesses - anything is possible. Unfortunately, the characters never really bond, at least not in a way that truly binds them together - not even thematically.