The one thing I'd
most like to see changed/added/improved, other than eye-candy issues, is: Race Habitability.
Take a look at Pax Imperia 2. Though most of that game IMO sucked (the
demo was better, argh), race design is a true gem.
First off, you could spend more points to breath more than one atmosphere type.
Second off, a planet's habitability was based on comparing the planet's atmosphere and temperature against what your race could breathe (a simple yes/no) and against your race's temperature-tolerance band (a weighted value; the closer to centerline you got, the better).
Thus, a world might be absolute hell for player A's colonists, and a pure paradise for player B's colonists. Player B will therefor value that planet more than Player A will, when negotiating colonisation rights in a border system -- though Player A would be best served by determining what player B likes, and pricing that world accordingly. And so on.
...
So; comparing to SE4/Gold ... allowing the selection of (for race points) additional atmosphere types would be great. Inserting a habitation value for temperature would be great. You could even go a step further, and add one for gravity, and end up with three variables to consider.
Next up, and also from Pax Imperia 2, is an issue I terribly miss in SE4: the issue of flag-versus-shipset. PaxImp2 has TWO seperate places to select those; your flag is one issue, your ship style is another. IOW, picking the (for example) Sallega shipset would not REQUIRE you (barring a customised copy) to use the Sallega flag. PaxImp2 has some 20-30 flags in it, most quite nice. Then maybe a dozen ship styles, also fairly nice (if only game play didn't suck).
...
Now, on to somehting I desperately wish could be added even to SE4, but would wait for SE5 to get if I had to:
NEGATIVE PREREQUISITES. Sorry for shouting, but this is something that most 4X games don't currently model: the concept that at certain key junctures (not every tech level, but every now and then), you get the option to "turn" your entire racial technology "paradigm" in one direction ... or another.
You can't do both. You can't have it all; research is no longer like Pokemon ("gotta tech 'em all"). If you get component X, you will NEVER have the option to get facility Y ... or vice versa.
...
Change the way minefields work. Make one "mine" built actually representative of a certain strength of minefield ... when it's laid into a sector (or whatever), that sector gets that strength of minefield. Based on the strength of the minefield, EVERY ship entering, or spending an entire turn inside, the field has a CHANCE, not an absolute, to take damage, based on the initial mine built. If they do, there's a (muchly reduced) chance to take MORE. And so on, until they stop taking damage.
Each impact reduces the overall strength ofthe field by a little. Minesweepers reduce the strength within a random range.
Um, here's an example, with out-of-thin-air numbers: Say each mine built at a world and deployed by a ship or base represents ... 20 points of "depth" for the field. Two minesweeper2 enter the field, able to sweep ... say, 4-6 apiece. Okay, let's say they get exactly average, and sweep 10 from that field.
That leaves a "depth" of 10, still. If we suppose the chance for a ship to be hit is equal to the field's depth, then each of the sweepes now has a 10% chance to impact a mine while sweeping. Let's say both do, but aren't damaged (they're heavily armored). Now, they each have a 5% chance to strike a SECOND mine; let's say only the second one does, and it survives, but is crippled.
Now it has a 2.5% chance (rounded however the program likes) to strike a THIRD mine (which might kill it); let's say it doesn't, however.
Three strikes happened; field depth is down by 3 more, and stands at 7.
Next turn, the defending player lays one MORE mine unit, increasing the strength by 20 more ... to 27. Obviously, those two minesweepers, ESPECIALLY the crippled one, are in trouble.
You can then introduce "decay", and even dispersal. Presume some fraction of a field is lost every turn, at a minimum; let's say 1/20th, or 5%. A 20-depth minefield, not swept and not run into, becomes a 19-depth field for the start of the next turn. If a single ship hits a mine, that satisfies the
minimum of one mine gone, so ... no extra loss occurs.
Dispersal can be modelled by increasing the decay rate, for any non-ship entity in the field (planets, moons, asteroid belts, wormholes, etc, etc). And/or decreased by the presence of minelaying ships or bases (who can tend to the field, retrieve strays, and so on).
Decay-and-dispersal represents mines simply drifting away, having their electronics packages go dead, hitting random spacejunk and going "boom", and so on.
...
Other than that ... well, 3D graphics isn't really a big requirement for me; "pseudo3D" would be fine (3d-looking, but still using 2D graphics). I must admit I like the idea of an animated solar system (again, see PaxImp2 for an example, complete with Warp Points). Obviously, in a turn-based game, the animation would be sort of stop-motion, but ... *shrug* ...
You could have the planets move at their own speed during the simultaneous-move replay. You could put a ring depicting the orbit of the planet, and brighten/darken/thicken/etc a segment to represent the planet's expected movement during the next turn.
Lastly,
KEEP THE MODDABILITY OF SE4. That's what prompted me to buy SE4/Gold, it's what keeps SE an actively-played game.
I'ms ure my other wants/needs have been brought up by others, but I'll post again if I see something's been missed.
Re: SE5, Tell Aaron what\'s on your Wish List
Even better would be to make the turns between sensor checks moddable, too. Yet another line added to settings.txt.... 
(yes, I know he probably will never see this thread...)
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