If you decide to make a custom character in Mass Effect, you'll be able to choose from one of six premade classes. There are three "pure" classes, which only focus on one of the three combat disciplines (soldiering, technical skills, and biotics), and three mixed classes, which combine skills from two of the three disciplines.
This section is going to offer a brief description of each class, but you should check the skill descriptions themselves for more info.
The soldier is the basic combat class of Mass Effect, and a fun class to play if you want to shoot stuff more than you want to worry about casting spells. There isn't much to say about the skills that they have on hand; they can specialize in any kind of weapon, obviously. You'll want to maximize Assault Rifles or Shotguns as a primary weapon, but you can also pick up Sniper Rifles if you want to have an alternate gun for long-range encounters.
Combat Armor will let you wear the heavy armor that will wind up giving you the most protection. First Aid will probably be something you'll want to leave to a teammate, like Liara. Assault Training can be good if you want to try your hand at knocking your foes around, while Fitness will be worth maximizing for the Immunity ability (which, in turn, can make it a lot easier to run around knocking enemies out).
- Assault Rifles
- (u)Sniper Rifles
- Combat Armor
- (u)First Aid
- Assault Training
We played through Mass Effect as an engineer for the purposes of this walkthrough and didn't have a particularly good time with the class. While you get the Pistols and Basic Armor required to be competent in a fight, the rest of the abilities of the class are generally rather passive. Decryption and Electronics are obviously needed throughout the game, and the Sabotage/Overload abilities are useful when dealing with opponents, but they aren't necessarily very fun to use, as they effectively debuff your opponents instead of killing them. We may be alone on this, but it's usually a bit more fun to cause your opponents to fly up into the air with biotics or power them down with assault rifle fire than it is to overload their weapons, however handy it may be.
A lot of the abilities here are kind of iffy, to boot. Hacking is useful for reducing the recharge rate of your abilities, but the actual AI Hacking ability will rarely be used except on turrets or drones, which are few and far between compared to the humanoid opponents you face (it can't be used on Geth). Damping is handy when going against biotics, but again, there are relatively few of those around. Medicine's Neural Shock ability is kind of useful, but only against a single organic opponent (i.e. it's not very useful against crowds and doesn't work at all against Geth or robotic enemies).
In all, our professional opinion is that you should bring along Tali or Garrus for tech skills and focus on biotics or soldiering for your own character. To each his or her own, however.
- (u)Basic Armor
- First Aid
Adepts are the biotic specialists of the Alliance. Although they can wield basic weapons and armor, their primary utility in battle comes from their biotic powers, which they can use to disrupt enemy advances and prevent enemies from attacking.
Biotics as a profession is a nice one; although biotic powers don't deal a huge amount of damage to your foes in most cases, they will be capable of stunning or incapacitating large groups of foes for lengthy periods of time, allowing your party to shoot them as they fly through the air, incapable of returning fire. The downside of being a biotic specialist is that there are a lot of skills that you'll want to invest in; Pistols and Basic Armor will be handy to have, while Throw, Lift, and Singularity will all be required if you want to keep your foes incapacitated for long periods of time, and Barrier will be needed if you wish to keep your shields up. And we're not even going to mention Charm/Adept and Spectre Training.
Still, you can get along well as an Adept without maximizing every single skill that you have, and placing the biotic powers of the team under your direct control will help minimize the sometimes stupid ways your AI teammates will use them. If we had a dime for every time Liara cast a Singularity at a crate two feet away from her face, we'd be rich. The ability to manually aim these powers will make them much more useful to you throughout the game, but you'll often be the weakest member of your party in return.
- Basic Armor