When I was a kid, riding the bus from the school to the local swimming baths so that we could all humiliate ourselves in front of our pitiless teachers, there was a fanciful game I used to play. I'd imagine that the bus was actually a great big simulator, with sophisticated 3D view-screens instead of windows. Instead of being driven to the baths, they were making us think we were being driven to the baths while a team of workmen busily changed all the outside scenery. For what reason? I had no idea. Possibly just to fuck with my head.
I've never really grown out of that mindset. I've flown between the US, the UK and Australia umpteen times, but I don't consider myself well-traveled. I didn't see much of the intervening places. From my perspective, I was in one place, then I sat in a big metal room for twelve hours playing Mario & Luigi, then I was in another place. For all I know, everywhere I've ever been is just over the next hill and there's some massive conspiracy to hide from me the fact that the entire world is about ten miles across, and to make me sit in uncomfortable chairs drinking vodka tonics for ungodly amounts of time. Anyway, the point is, that's what Mass Effect 2 reminded me of.
As Douglas Adams once said, with his usual spectacular insight, space is big. It's so big that any story you set in space immediately gets an epic sense of bigness about it, just by virtue of being next to all that big. In theory, anyway. My main problem with Mass Effect 2 was that I didn't really get that bigness feel. It felt like every location in the game was within easy walking distance of each other.
Here's how you get around: you start off in your spaceship wearing casual gear, then you go to the navigation desk. There you pilot a miniature version of your ship around a little train set-sized galaxy and dock it in one of the dockable locations. Then fade out and fade up on your character in body armor sauntering into the new location, where (s)he will presumably partake in some angry conversations and gunfights. And once you've finished your missions, we fade out and fade up on the ship again, back in your slippers and future space pajamas.
See, for all I know the Normandy is docked in a garage somewhere, and all the locations I can visit are all set up in a big warehouse around the corner. For all I know my character is slipping into a coma whenever he uses the navigation console and everything off the ship is a fever dream. For all I know this is some Killer7-style arrangement - the Normandy is actually some bizarre astral realm, Pajama-Shepard is some kind of overseeing god-like entity, and Armor-Shepard is his corporeal avatar. You see what I'm saying? There's little sense of physical connectivity between any of it, and that hurts the immersion.
Now, when I was a kid, I used to play Frontier: Elite 2 on my Amiga 600, and I would get embarrassingly into it. I didn't even understand half of what was going on, but I could spend hours flying through the physical space between stations, exploring the universe. I used to rock back and forth in my seat whenever I banked to simulate the movement. And whenever pirates blew me up I'd hurl myself off my chair yelling KABOOM. Now, Frontier had an awful frame rate and was composed entirely of untextured polygons, but I got so shamelessly immersed because the action never cut away. You could descend from space to a planet's surface and land manually, or dock in a rotating space station 2001-style. No fade-outs skipping the parts of the journey you didn't have to watch - a constant physical transition from A to B. That's what I mean by connectivity.