Defender is correct on wayfar1444, though it is a mud not a browser game you can find It's homepage here which has more info.
My only problem with wayfar is firstly finding resources is a pain, sinse as the overview ascii map isn't accessible you don't know what biomes are around you on a planet, and though you can freely search for stuff running around a 100 x 100 map looking for sand isn't fun .
I did suggest a "biome finder" to give you directions to somewhere, and the developer thought it was a good idea, but I don't think it ever got added.
My second problem with Wayfar1444, is that once I'd built my colony the game became a lot less interesting, sinse it basically devoled into looking up very complex recipes for crafting and making stuff, with your colonists not being much help. I'm told things got more interesting when you get out into space and could fight npc pirates. Also, there was potentially unrestricted pvp in the game, sinse there was nothing to stop people blowing up each other's buildings or hacking each other's vehicles and electronics, althugh in practice this didn't seem to happen often or indeed at all.
I've been looking for that Pve empire building game myself, but it's sadly not come around, at least not online. Core exiles is your best bet for that sinse the only pvp there is price competition on the market. Your best off looking offline for something space based and pve. Smugglers 3-5 and star traders are more like trading and turn based ship combat with managing in a war between different factions, though in the most recent version of s5 you can be a pirate and build your own pirate empire.
They're not exactly what you want I think sinse it's more about the trading and exploring and fighting than the building, although stratogy is still needed (both series have pretty complex combat in their own ways), but if your not looking for a grindnbash online they're probably your best bet.
For more on smugglers, check out My smugglers 5 introductory podcast here on sendspace
and of course The db page for smugglers 5 and The db page for the smugglers 5 invasion expantion
And lastly The db page for star traders and This introductory article I wrote on the game.
Hth.
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)