Overview:
-Estimated achievement difficulty: 9.5/10
-Offline: 52 (825)
-Online: 6 (75)
-Offline/Online: 1(100)
-Approximate amount of time to 1000: 80-200+ hours
-Minimum number of playthroughs needed: 8 (Single player and Co-op)
-Number of missable achievements: 1 (If you want to glitch it)
-Glitched achievements: 6 “good glitches” (50)
-Do cheat codes disable achievements? Sometimes (see below)
-Does difficulty affect achievements? Yes

I gave this game a 9.5 difficulty rating because of how extremely hard some, if not most, of the achievements are. Even if you are a really good Guitar Hero player, this game still will be challenging, as all of the Guitar Hero games are. I rated it 9.5 due to the incredible amount of effort that you need to put in to get good at the game and to complete some of the harder achievements.

Introduction:
Guitar Hero 3 is an extremely difficult game to 1000[. You will have to hit lightning fast notes at high speeds with very little reaction time. You will have to be able to effectively tap on your guitar for some achievements. You will also have to perfect 20 songs on the Expert difficulty. Don’t get me wrong, guitar hero is a really fun game. However, only the extremely committed will be able to get a full 1000 in this game.

In order to hit notes that come down the screen, you must both hold the fret(s) (button(s)) that you want to play, and strum with the strum bar. This is similar to playing a real guitar. All the other basics will be laid out in the tutorials. Once you get to Expert difficulty, and need help with Enlightened Guitarist and other hard career achievements, consult this thread HERE.
This thread was created by Lordvader178.

There are at least 8 playthroughs needed to beat this game. However, if you can’t 5 star (“5 star” is a verb which means get a 5 star rating on the song) all the Expert songs on your first try, it will take many more playthroughs than that. I consider a playthrough completing every song in a career. The method I describe in my Road Map assumes that you have no Guitar Hero talent whatsoever. This requires 12 playthroughs, assuming you have an able friend who can play expert bass/guitar with you by the time you finish 5 staring your expert songs.

There are 2 glitches in this game, and both of them aid you in getting achievements. However, one of them is missable and you only have two chances to get it. This is the Buy a Guitar Already achievement. This achievement is obtained at the end of your hard/expert career. I highly recommend you do this glitch, due to the fact that playing on a controller is much harder than on a guitar. The other glitch cannot be missed.

Here is the “Unlock Everything” cheat that gets you these achievements in the game: Axe Collector, Track Master, Got 'em All, and Burning a Hole in Your Pocket. All the other cheats disable achievements, so don’t bother with them. Enter it in the cheat code section of the game, found in the options menu on the game. Go into options, and then select “Cheats” at the bottom. Do this after you have beaten Expert career (as described in my Roadmap).

Unlock Everything:
(+)(+)(+ )(+)(+)(+)(+ )(+)(+)(+)(+)(+)(+)

You will not get a noise when you enter these chords in. To enter a chord in, hold all the correct frets and strum. Then proceed to the next chord, and continue.

You may start to become very stressed out when getting to higher difficulties and harder songs. I remember giving up 3 times, when I started Hard career, when I started Expert career, and when I got to the last tier of Expert career. The trick is to not give up, and keep pushing on. Like many sports, you will get better at Guitar Hero with time and practice. Also, practice mode helps a lot when you are struggling with songs in the last few tiers.

Abbreviated Walkthrough:

• Step 1: Start off by completing all 4 tutorials. You will get Ready to Rock. Be sure you use the right fingers for the notes, and strum pushing down with your thumb/strumming up and down with you index finger and thumb. I find it easiest to strum pushing down with your thumb for slow moving notes/ inconsistent notes, and strumming up and down for fast notes with a consistent beat. Try not to get into too many bad habits, and listen to what they say.

NOTE: Pay extra careful attention to the hammer-on/pull-off section. This will be heavily used in Expert songs.

• Step 2: Beat Easy career. Don't worry about 5 Staring songs; just try not to get into any bad habits. You may get Bronze Streaker and Silver Streaker while doing this. Be sure to pick up the Whammy Mania near the end. You will get Easy Rider.

• Step 3: Now beat Medium career. It will be really hard to hit the blue notes early on, but just remember to use your pinky finger and don't get into any bad habits! I cannot stress this enough. Some of the later songs will be hard, just keep trying and use practice mode. Also, go for Tail Between Your Legs, Blowin' It, and Almost Got It. You will get Medium Rare.

• Step 4: Time for Hard career. When trying to hit the orange notes, your fingers will undoubtedly feel like they are glued to the guitar. Don't stretch for the notes, but move your hand like you would on a real guitar. This means sometimes your fingers won't be touching the green note, and the other times the orange one. After the first tier, you will get the hang of it. Once you get to songs in the 7th and 8th tier, you defiantly will need to use practice mode. Don't get frustrated, and you will eventually get it. You will also most likely get First Big Score and Gold Streaker while completing this career. You will getAlways Hard.

VERY IMPORTANT: If you want to save yourself a lot of time, go for the glitched Buy a Guitar Already achievement.

• Step 5: Now start a brand new band and go to Easy career. Switch your guitar to lefty, and use the mirror looking trick to beat it (the mirror trick is: look in a mirror that is facing your TV with lefty flip on, and when you look in the mirror it appears as if lefty flip is off). Aim for all 5 Stars, which should be very easy. After you get Axe Grinder, go and beat Medium career on that new band, but without lefty switch turned on, and get 5 Stars on all songs. You should get Hendrix Reborn and Rock Guru. If you miss a 5 star on any of the songs in your setlist, don’t worry you can always retry a song. Finish 5 starring any songs you missed in medium and easy.

• Step 6: Complete Expert career on your original band. This will be very hard in the 6th/ 7th tier, and excruciatingly hard in the 8th tier. You will need to hit 3-note chords with ease, and you will constantly have to move your hand down and up on the guitar neck. You must also be exceptional with hammer-ons. But don't let me scare you; with hard work and practice mode, you should be able to do this. If you’re having trouble with the final battle, use this video:

           I take no credit for this video, it is not mine. Once you’re done, you should get Right Hand of God and Solo Career. Also, go for Tone Deaf on expert Slow Ride.

VERY IMPORTANT: If you forgot to get Buy a Guitar Already on your Hard career, do it now! This is your last chance to get it without having to play career again!

• Step 7: Go back to Hard career on your original band and 5 star all the songs. They should seem easy compared to expert, but the last 2 tiers might take a few tries and some practice. If Raining Blood is giving you too much trouble, skip it and come back to it later when you are better at the game. You will get Shredder.

• Step 8: Get Axe Collector, Track Master, Got 'em All, and Burning a Hole in Your Pocket. You can either do these fair or enter in the "Unlock Everything" cheat in the cheat menu. Look for the note sequences in my Road Map introduction.

• Step 9: Go back to Expert career and shoot for Enlightened Guitarist and Guitar Hero. When you get bored of one, try the other. Along way, you will get Perfectionist. Also, if you don't have Streak Master, Even Flow has over 1000 notes and isn't that hard for an experienced player to FC (“FC” mean “Full Combo”: You hit all the notes in a song). Also, when you get to Cult of Personality, get Who Needs the Power.

• Step 10: Get a friend over and do all the Co-op Career achievements. Achieve Easy Duo, Medium Duo, Hard Duo, and Living Legends. Living Legends will be hard, but with constant practice and lots of effort you should get it. You should get Two by Four, Half a Mill' Club, Leaders of the Pack, Dynamic Duo, Two Timer, A Couple of Streakers, Too Many Too Count, and That's What Friends are For. Also, work it out so you get Guitar Wizard, and Back Up Hero. Also, go for Streak Masters.

Step 11: Beat Through the Fire and Flames on Expert difficulty. Be sure to do it on quickplay, or else it won’t count! Use one of these tapping guides for the beginning. I do not take credit for either video. The way the first person strums is with his elbow.