- Estimated achievement difficulty: 1/10
- Offline: 39 
- Online: 0 
- Estimated amount of time to 1000: 5-20 hours [depends on skill]
- Minimum number of playthroughs needed: 6
- Missable achievements: None
- Cheats disable achievements: No cheats
- Does difficulty affect achievements: Yes [6 achievementss require completion of new order/arcade mode on easy/normal/hard difficulty]
- Unobtainable/glitched achievements: None
Remake of a popular shoot 'em up game originally for Dreamcast. It includes a newly arrange mode called New Order mode as well as the original Arcade mode. The game is re-rendered in beautiful HD graphics making it well worth the purchase if you are a fan of the original game. Also, if you are an achievement hunter, this is a great game to get because it is extremely easy to get the 1000.
If you have already played this game or if you are pretty good at shoot 'em ups you can try and go for the achievements the legit way or you can just turbo to get the credits to Free Play and then go for the achievements. You get one credit per hour of play, and after 9 credits it goes to Free Play, so you need 7 hours of New Order and 7 hours of Arcade mode to unlock Free Play in each of those modes.
Here's the basic of what you need to do in order to get 1000 in the game:
1. Clear the New Order mode twice. Once on Easy difficulty. Once on Hard difficulty.
2. Clear the New Order Extra mode once on Normal difficulty.
3. Clear the Arcade mode twice. Once on Easy difficulty. Once on Hard difficulty.
4. Clear the Arcade Extra mode once on Normal difficulty.
5. Mop-up: Getting 100% shoot down rate, etc. Refer to achievement guide for details.
As you can see, once you have unlocked Free Play, it is a trivial matter to complete the game. If you do not need Free Play, you can technically get the 1000 in the game in 4 hours. If you need to unlock Free Play, you need to add 14 hours, making it 18 hours. Either way, you will have 1000 in less than 20 hours.
[XBA would like to thank sanger for this roadmap]