- Estimated achievement difficulty: 3/10
- Offline: 12/12 (200)
- Online: 0 (0)
- Approximate amount of time to 200: 10 - 15 hours
- Minimum number of playthroughs needed: 1
- Number of missable achievements: None (Stage can be replayed)
- Do cheat codes disable achievements?: No Cheats
- Does difficulty affect achievements?: No
- Glitchy achievements: None
- Unobtainable achievements: None
- Extra equipment needed?: None
Step 1: Campaign
The first thing you need to get out of the way (since it's all you can play at the moment), is at least the first section of the campaign. The premise of the campaign is basically the reverse of any traditional tower defense game, where you play the attackers invading and destroying the towers. Each of the campaign levels is relatively short and not too difficult aside from a few missions near the end of the campaign. As you progress through the campaign you will unlock the other game modes necessary for the other achievements, as well as get a good portion of the tower kills for Avenger.
Step 2: Baghdad Mayhem
While the unlocked modes don't need to be done in any order, this mode is unlocked about halfway through the campaign so it can be completed first. In order to win, you need to finish 10 waves of enemies and a generator, with each wave giving you 5 minutes to destroy the generator and activate the next wave. Enemies do not despawn between waves so you can get overrun if you don't stay on top of killing a majority of the enemies each wave. As you progress through the waves, the enemies that spawn will become more and more diverse, introducing the harder towers at the higher waves. A basic strategy of balancing your time and money with your number and type of units will make this mode go smoother, but overall it's not too difficult. Losing your whole convoy at any point means you have to start over.
Step 3: Tokyo Raid
This mode consists of 18 unique maps, or islands, that you must pass through by completing various objectives in each. Being smart about using your commander for a distraction and keeping your units healed will help a lot in the early waves, which in my opinion are the most annoying due to your limited number of units. Make sure you pay attention to the objective and the clock because losing in any of the waves means you start over from scratch.
Step 4: Baghdad Mayhem Rearmed
Just as the title states, it's the same as Baghdad Mayhem, but with more waves and more units. Units also appear sooner in the waves, meaning you have to start preparing for the deadlier towers early on. Utilizing hit and run tactics on the towers surrounding the generators, as you work your way to the generator itself, will give you both room to breathe when you make the assault on the generator, and also the cash you need to upgrade your units. This mode isn't all that much of a leap in difficulty from the regular version, in fact once you get to the last few waves your convoy will probably be steamrolling the enemies (unless you made a mistake). As with the other unlocked modes, if you lose everything, you start over from wave 1.
Step 5: Trials
Trials are a number of very minor missions, each with their own objective for you to accomplish. They are all really easy to just finish, without focusing on your score, aside from the last one which can be pretty tricky. Luckily, I included a brief strategy (well, rather wordy, as they are really simple) for each to help you out.
Step 6: Clean up
By now all you should have to finish is Avenger, and you should be - I would estimate - about halfway there depending on how successful you were with the unlockable modes. To make it fun, less pointless, etc, I would just recommend you go back and try to up your scores on the campaign/other missions, or just use the strategy listed for the achievement.
[x360a would like to thank Shiftie for this roadmap]