For the first six months they were making it, the creators of "Guitar Hero" for the DS weren't sure their game was going to work.
Then things got better.
And from what I saw and heard when the game was demoed for me in New York City a few weeks ago, the DS experts at Activision's Vicarious Visions studio have solved most -- maybe even all -- the challenges they faced.
Here are the obstacles this game faced en-route to its eventual release in June and what I learned about them during the demo I got of the game:
Challenge #1: The DS Is Not Shaped Like A Guitar
"Guitar Hero On Tour" simulates guitar playing with the help of a plug-in four-button fret. The packed-in add-on, a "Guitar Grip," jacks into the Game Boy Advance slot of the DS Lite (and ships with a small extension that allows it to plug into the original DS "fat" too. The player wraps their fingers around the peripheral as if it was the neck of a guitar, cradling the DS like it's a book. They strum notes using a specially designed guitar pick that has a stylus tip at the end. (See the game played in this trailer.)
Vicarious Vision CEO Karthik Bala told me that the team never even considered using the add-on neck idea that showed up on some blogs. It would have prevented the game from being "compact."
Challenge #2: It's Not Easy To Add Buttons To The DS
... Especially When Nintendo Is Paying Attention
"We built like 20-something protoypes," Bala told me. "We built a cardboard guitar and taped the DS onto it, to have the touch screen be the buttons. That didn't work so well."
He said prototype #13 involved taking apart a Game Boy Advance cartridge, adding some switches and figuring out how the DS could detect input from those switches. That's the idea they went with: literally plugging new fret buttons into the DS.
Note how radical an idea this is. It would be like turning the disc-drive of a PS3 into an extra controller slot. "It was an interesting breakthrough because in a console game, the buttons on the guitar match the standard controller buttons. That's not how this works. This is actual physical new input. It's not hijacking buttons on the button map."
Nintendo had to approve this manipulation of their machine. "It's no small feat developing a new piece of hardware that will meet Nintendo's high standards." Bala said. The Vicarious team worked closely with Nintendo engineers to get it right.
Challenge #3: The DS Doesn't Necessarily Have Room For A Five-Button Fret
"We tried five buttons," Bala said. "In fact we tried six buttons. We also tried 11 buttons, but that's a different story. It actually came down to making a decision between making a four-button and a five-button controller. What we found is that five buttons is not fun because moving your fingers up and down the guitar grip would cause the DS to shake. You'd lose where you are on the screen. It just wasn't fun."
Having just four buttons doesn't make the game any easier, Bala said. "We still wanted to make sure the game had an expert mode. And expert mode is for experts. The tuning of this game is designed for this kind of input."
Challenge #4: The DS Isn't Built To Provide Console-Quality "Guitar Hero" Graphics And Sound
That didn't stop Vicarious Visions from trying.
Technologically, this game marks a highwater mark for Vicarious Visions, a studio that has already pushed the DS harder than most studious outside of Nintendo. "Each character is around 2200 polygons," Bala said. The most-detailed character Vicarious Visions had previously rendered on the DS were 600 polygons. As for audio, it's streamed in three layers: guitar, rhythm bass, and the rest of the song. The game includes over 100 minutes of music, 85 percent of them master tracks. "To fit that all on the cart and have the game run at 60 frames per second is a significant challenge."
Challenge #5: "Guitar Hero" Needs Good Multiplayer, But Two People Can't Crowd Around The Same DS Screen
"Guitar Hero: On Tour" features a franchise-first Guitar Duel mode. The technological achievement of the game may have been the most dazzling aspect of Activision's demonstration of the game for me, but the Duel mode was definitely the most enticing reason to want to play it.
Bala and Activision spokesperson Kehau Rodenhurst synced two DS systems via wireless and had a duel. Their match was a mix of "Guitar Hero" and competitive games like "Puzzle Fighter." They were able to earn weapon items and attack each other with them.
Weapons included a string-breaker that requires the player to re-draw their guitar strings, a screen flip that moves the action onto the DS' other screen, a pyrotechnics accident you have to blow into the DS mic to extinguish, a hyper-speed setting, an item that mutes the music on the other player's system, and several more.
Challenge #6: Despite Everything Said Above, A "Guitar Hero" Game Without A Guitar May Not Allow Its Player To Feel Like A Guitar Hero
How can a player feel like a rock god when they're strumming a little book-shaped Nintendo DS?
Bala said the lack of a guitar did make this challenge tough. "At the same time," he said, "The core aesthetics as you're playing through the career progression: you connect with the characters, you connect with what you're doing. And especially if you're playing at the higher difficulty, it really does feel like you're playing like an instrument. Although it's more abstract and it's not a guitar it evokes some of the same sensation."
I went into my demo of "Guitar Hero: On Tour" skeptical, but what I was shown was impressive. "It was really a grassroots approach with a team that was hell-bent on making it work," Bala said.
From first impressions, I think they may have pulled it off.