1. Larger scale environments, combat, and gameplay- This is it. This is the climax that Mass Effect fans have been waiting for. It goes without saying that ME3 should be more epic in scope. I'd most like to see the opportunity to bring more squadmates along for each mission. Plus, seeing as the galaxy appears to be engulfed in full-scale war, it would be nice to see Shepard and the team fighting alongside various factions' armies. Larger mission maps would be cool, too. I hope that Bioware adds more open environments.
2. More dialogue and interaction- I know this is asking a bit much from Bioware already, seeing as they set the bar for dialogue and interaction in RPGs, but this would still be nice. Perhaps some more varied dialogue choices for Shepard with an indicator as to how the response willl sound, a la DA2. It would certainly add some depth and uniqueness to one's own Shepard. More interaction with your squad could be nice, too. More idle banter, probably some combat dialogue, and definitely more conversation options. Some of the previous requests for this have some good examples. Maybe the option to take the crew out for some R&R or something. Maybe, after a successful mission, you could get the option to congratulate your team or discuss the mission. I don't know about the rest of you, but I want the option to fist-bump Garrus and Wrex.
3. A setting that evolves over time- This might also be difficult, but it would be a nice touch. We should get a sense of progress of the war as the game progresses. Some off-hand news reports, e-mails, and cutscenes would be cool. For example, one might visit the Citadel early on to see just the Destiny Ascension and a few Turian and Asari ships defending it. Later on, perhaps we see that the defenses have been bolstered by large numbers of Alliance vessels, the Migrant Fleet, and (if you saved them in ME1), Rachni...I don't know, Bio-Ships, maybe.
4. Less linearity- Different routes to take throughout a mission would be sweet. Maybe not the smaller-scale, covert missions, but maybe larger scale battles. Shepard could be given various objectives scattered around the battlefield and it would be up to him to decide which ones to solve and in what order. Some of those objectives could be optional faction-specific ones to determine whose side Shepard is on--Alliance or Cerberus, Geth or Quarian, etc.
5. Concerning party members...-While it would be nice to see the everyone from ME1 and ME2 together as recruitable squadmates, it shouldn't be mandatory or that important. Some faces I'd like to see back in the party roster, though, would be Tali, Garrus, Zaeed, Liara, and Wrex
(Shepard). As stated above, more interaction would be awesome. Loyalty quests were great in the previous games, but I'd also like to see (small) loyalty quest
chains,a la DA:O. A sense of bonding and progress in your squad should also be visible. Some character-specific conversations like in DA:O would be great. As time goes on, maybe Shep's old squadmates from ME1 and 2 should warm up to each other/to new arrivals.
6. Concerning memes, pop culture, and call-backs...- Recruitable Blasto? Please? I'm hoping for "Don't Fear the Reaper" to be either part of the soundtrack or a quest name. And if they're going to reveal Tali's face, it has to be tasteful. It should be an important part of Shep and Tali's relationship, not just as something tacked on to pander to the fanbase. Better that she remain faceless to the player than her reveal be anticlimactic or poorly executed (But this being a Bioware game, I doubt it will be either). I also want to see Niftu Cal, BIOTIC GOD, as a recurring character. He could be comic relief or he might have learned a thing or two about sweeping people away like a great biotic wind between games. I'm also strangely interested in the ME universe's media and entertainment--I really want to see Elcor Shakespeare for some strange reason. The option to call out Councilor Velarn on his dismissal of claims in ME 2 is an absolute must. And, just for fun, maybe a little side quest with Shepard and crew investigating crime on the Citadel? It could be called "CSI: Citadel Security Investigation" and Shep and/or his squad could throw around pithy one-liners with obligatory glasses pulls and The Who.
7. Wrex - Shepard.
8. A combinationof ME1 and 2 gameplay elements- ME2's combat was great, but I found it my squadmates' abilities lacking in variety. Maybe expand their range of powers, but not to the extent of ME1's. I also would like guns to include both the thermal clip and overheat functions. Maybe guns could be set to the standard overheat setting for basic combat, but Shepard can cycle a fresh thermal clip in when he/she wants to keep up the fire without waiting for the cooldown. Equipment upgrades and customization should also incorporate elements from both. Loot or purchase guns, armor, attachments, and parts from corpses, stores, or Space Ebay and then spend resources to upgrade them. For example, one could pick up a heatsink and then spend X amount of unobtainium to decrease cooling time and/or increase heat capacity. ME1's inventory system, while problematic and slightly annoying, was overall, pretty good. I just didn't like cycling through endless lists of vendor trash and omni-gelling everything. Looting blueprints or weapons/armor parts that you don't already own could be a nice way to fix this. Combine this with ME2's less RPG-ish weapon system (everything having pros and cons to balance them out). I also liked the Mako, but hated its handling on steep surfaces and the relative emptiness of the levels. Give back controllable vehicles, but make them easy to use and their levels smaller/more populated.
9. Mini-games - Should be kept to a minimum, if even present at all, unless they're fun or relaxing. The hacking sequences might be considered small mini-games, for some. I don't know about everyone else, but I enjoyed ME2's hacking, if only because they provided a nice break from the fighting and seemed more hack-ish than ME1's button presses. An auto-hack option would be nice, but I don't want to have to omni-gel random bits and pieces to be able to do so. That card game Shep can play with Ken and Gabby (Skyllian Five, IIRC) would be interesting. It would be funny if we found out that it was just Pazaak (IN
SPACE MASS EFFECT!). Maybe a flight/space shooter featuring the Normandy, a la Starfox or Galaga. Admit it, 8-bit Normandy would look like a palette-swapped sprite of the Galaga player spaceship. For some reason, I can also imagine an 8-bit Megaman-esque platformer version of ME1. Maybe I'm just weird.
10. Planets- Fewer uninhabited/sparsely inhabited border worlds, please. While they make for some fun side adventures, I felt that they detracted from the story most of the time. I'd like to visit more inhabited/urban planets and possibly some species' homeworlds or major planets--Earth, Palaven, etc. The Hanar homeworld would be cool. Heck, Bioware could just reuse Manaan from KOTOR with some spruced up visuals and Hanar and Drell in place of the Manaanites, Sith, and Republic.
11. Customization- I liked ME2's armor and casual outfit customization options, so perhaps Bioware could take it a bit further (reasonably, of course)? Maybe throw in some personal touches to the Normandy's paintjob, like replacing Cerberus insignia with Alliance iconography or some hot rod flames...Yeah, hot rod flames. Also, just for lulz, maybe the choice to make Male Shep sound and look like Nathan Fillion?...What?