No spoilers for Mass Effect 3's ending! Safe to read for most people.
Everybody knows that Mass Effect 3 is the end of Shepard's story – Bioware has been saying this since they announced ME3. Everybody also knows that ME3 is not the end of EA's production of games and products within the Mass Effect universe. Whether Bioware is involved or not (frankly, whether they are interested or not) EA is going to publish more games that make use of the richly developed setting that is the Mass Effect universe.
Because you're reading this on the internet, there is a good chance that your reaction to that reality falls somewhere between starting to compose a 'boycott this' post and spontaneously rage-chewing the arms off your chair. Frankly, when they announce “Mass Effect Wars” the RTS and “Medal of Honor: Turian Infiltrator” I'll be right there with you.
Until then, it is more productive to accept that EA is going to be EA and act in the interest of its shareholders by putting out more products that leverage the Mass Effect IP. In fact, the best thing you can do is start thinking about how these games could be made in a way that won't eventually justify chair-biting. So I spent a little while brainstorming some reasonable game proposals, and uh, here is one.
The game proposal that I think would work the best would be to build a character action game around Jack. Jack, the powerful biotic (that is, space wizard or ersatz force user), would be a strong personality to wrap a game around. A dynamic action game, not built on shooting or RPG conventions would be distinct enough from the core Mass Effect trilogy to make it a clear spin-off that can stand on its own, safe from accusations of just being cut content. The Mass Effect universe has a wealth of strong characters, but I think that Jack is one of the most distinct individuals who could also support a game in a non-Bioware genre (I mean, I love Mordin, but I don't see a non-ME style game built around him off the top of my head).
Jack was abducted as a child and was subject to horrendous biological and psychological experiments with the goal of making her a living weapon for Cerberus, a terrorist human-supremest organization. If you've played the games, you know that Jack escapes as an adolescent, slaughtering everybody else in the facility. Cerberus succeeded in greatly amplifying her biotic abilities, but only managed to turn her into a terrible person, rather than a leashed human weapon. Not at all another square-jawed space Jarhead taking orders over the phone, Jack would be a breath of fresh air. In fact, she would be a little more like Kratos; self-directed and not always reasonable or justified. Also bald.
Hand it to another dev team with high action chops, build it on an engine tuned to fast and fluid action, and amp up the in-game depiction and functionality of Jack's biotic abilities to meet what we have been shown in cut-scenes.
In cut-scenes, we see powerful biotics wrapping themselves in a biotic field in order to jump and fall great distances, build massive barriers to resist gunfire and explosions, and create shearing force powerful enough pull the arms off a YMIR mech. In-game, the Vanguard class to which Jack belongs gets the 'biotic charge' power, which is headlong rush directly at an enemy that boarders on being a teleport.
With all of that taken together, I can easily picture an action-oriented game somewhere in the range of Vanquish to Ninja Gaiden that features Jack only occasionally armed with her shotgun. Instead relying on a toolbox of biotic powers as she warps around a combat scenario -- holding up barriers when shot at, super-jumping out of the way of danger, and just fucking destroys people (criminals, mercenaries, and especially Cerberus forces) who get in her way. Because this is a stand-alone game, I would be game for graphic telekinetic dismemberment and a much more raw tone to reflect Jack's personality, as opposed to the mostly bloodless world of the main trunk ME games.
In regard to narrative I would set the primary A to B continuity to start at Jack leaving the Normandy at the end of ME2, to finding purpose and a constructive role for herself in the situation you discover her in ME3. The theme would be her digesting the growth experiences and drastic events of Mass Effect 2, perhaps making something like an apology tour, whether she actually engages the victims of her excess and recklessness or just reflects on what brought her to those extremes.
Much of the gameplay would take place in flashbacks based on her backstory and anecdotes from ME2. Obviously, you need to cover the brutal treatment and gladiator pit-like training, and eventual escape from the Cerberus project lab. You also need to address her capture and maximum security confinement, which is the situation in which she meets Shepard. From her shipboard dialogue, we have other colourful events outlined including spending time in gangs, a cult, crashing a space station into a moon... All of which could be fleshed out into exciting and dynamic action sequences.
The richness of Bioware is in their character writing and the construction of interesting and well thought out universes (their success or failure in game scenarios is more subjective). Making an RTS or FPS which doesn't leverage direct control over a major established character is a mistake that EA should avoid (but probably won't). These are the easiest and least imaginative spin-offs, but they would be a mistake.
Mass Effect 3's Galaxy at War mode obviates the need, and even the place, for a multiplayer-focused shooter, at least for the first wave of spin-off products. EA owns or deals with many competent shooter studios, so they could set a developer to the task tomorrow if they wanted. Making a conventional FPS is most obvious and least inspired thing EA could do, and I feel pretty confident it would be a PR loser for them. Too many shooters on the market already, and slapping the ME license on one would be greeted with skepticism and resent by a playerbase already suspicious of EA/Bioware's handling of the main franchise.
The temptation to make an RTS game must be pretty great – especially in light of the studio EA renamed “Bioware Infinite” is already working on a Command an Conquer game. We've seen this before with Halo Wars, and it went over like a lead balloon. Mechanically, making an RTS out of the ME universe would be difficult. Halo has a better, if still anaemic roster of skirmish fighting units, and they struggled with balance and believability. Fact is, console RTS games suck, and this kind of game would need to be multiplatform to recoup development costs. Blizzard's StarCraft franchise is the only current success in the RTS field, so between StarCraft expansions and the forthcoming C&C game, a Mass Effect RTS would flounder.
I think that EA has to avoid these kinds of obvious and easy projects when the look at their spin-off options for the Mass Effect universe. Something more like my Jack character action game would be a better solution. EA can succeed by showing respect to the existing relationship between players and important characters in the ME trilogy, by avoiding cliched and crowded genres, and by creating a game solid enough to stand on its own – a game enhanced by the license, not carried by it.