Harmonix and Mad Catz are at E3 2015 in Los Angeles, where they are showing off the fruits of their new partnership: Rock Band 4 with all-new controllers. We met with Daniel Sussman, who has been with Harmonix since 2001 and now serves as a product manager, to get an overview of the upcoming game's new features as well as play with the new guitar and drum setup from Mad Catz.

Starting off with the gameplay, Sussman told us that Harmonix wanted to add features to the Rock Band franchise that would do a better job at pulling gamers into the fantasy of playing live music. There are a few ways the developer went about tackling that goal, and one of them is a new freestyle guitar solo feature that - rather than play the recorded song like normal - allows you to play as you wish.

The feature works with any song that has a guitar solo (although the Rock Band catalogue has a few songs without guitar solos, such as Suspicious Mind by Elvis Presley). Harmonix is still working through its back catalogue of more than 3,000 songs (which Rock Band 4 will support) and adding the new feature to them. We got to play a guitar solo during a demo with the song Footloose, and it was awesome.

It actually reminded us of the improvisational drum-fill sections found in the other Rock Band titles, but these solos are meant to give you some more creative leeway as well as make you feel like a true rock star. When a solo is a available, you'll see on-screen patterns that indicate how to play. You can finger tap away or hold a long note or play a chord, using buttons on the top or bottom of the new guitar's neck.

Your solos will always be in key; you're scored based on how well you followed the game's suggestions. We didn't really follow the suggestions and were told by the game that our solo was "messy". Ha. We just didn't care about the score and rocked out (admittedly, we found the colours and patterns confusing to grasp at first). If you want the more traditional gameplay, you can always disable freestyle.

Sussman also showed off an improvisational singer feature in the upcoming game. Rock Band basically knows what key the song is in and the pitch of your the vocals, but now, it doesn't have to hold you to single notes. As long as you're in key and singing as you wish, you'll be rewarded in the game. The crowd will be more responsive to this as well and might demand an encore, which you can sing or not.

Another new innovation is a “play a show” feature. Basically, it works like this: when a group of friends are playing together, they can either play a single song or an extended multi-song show. Also, after each song, band members can vote on whether to keep playing and which song they'd like to play. You'll be presented with choices like female vocalist or 80s music or even a list of songs.

From there, each player can vote with their controller in order to decide which song they want to play, and then the game will automatically decide the winning tune and serve it up: "It's a great way to explore songs...you're being forced to try something new, some song you might not normally select," Sussman explained. "We like to think of Rock Band 4 as a music-discovery vehicle."

Apart from that, Harmonix and Mad Catz took time to explain and demo the new controllers. They reiterated that the old instruments will work on the new-generation consoles from the same manufacturer, but Mad Catz's new line of plastic instruments will offer slight improvements. The Rock Band 4 guitar is a wireless Fender Stratocaster. You can pre-order it (comes with Band-in-a-Box bundle) now.

The Band-in-a-Box bundle includes Rock Band 4, the guitar, a wireless drum kit controller, and a USB microphone. We only played with the guitar. It has new frets with positive force actuation, which means they are quieter to play and provide tactile feedback when clicking. Other features include 30-hours of battery life, redesigned tilt sensor for overdrive activation, and two sets of fret buttons.

The two sets of fret buttons are perfect for boosting your score in freestyle guitar solos, Sussman told us. We also saw the new drum sets for Xbox One and PlayStation 4 on display, but we didn't get a chance to actually play them during the demo. We were told the new drums have reinforced pads and drum pedals. The kit also allows for a dual drum-pedal setup out of the box.

Last, but not least, Sussman revealed more than 1,500 songs are planned to be compatible with Rock Band 4 at launch, and Harmonix is planning to push updates and release DLC packs with new songs over the next 4 to 5 years (essentially turning the game into a platform).

When we asked about any potential social elements within the game, Sussman said we can expect to hear more about that later this summer. And a few months after that, on 6 October, the fourth main installment in the Rock Band franchise will officially release for PS4 and Xbox One.

Mad Catz, who is exclusively developing new instrument controllers for the game, will market and distribute the title worldwide.