I've been meaning to cover this one for quite awhile in more detail. Awhile back, I came across a 2d MMO that I really got hooked on for a bit and that was Starport: http://www.starportgame.com/
First off, let me explain there are many different server types like Hardcore, Casual, and Mid way. I spent my time on Begininer's Galaxy however- the PVP server for begininers. Now here is the twist on this server: its a limited time span server. You have a fixed length of time to explore the universe and conquer it then the world is reset. I spoke to one of the devs about which server I should tryout and he strongly suggested this server.
It seemed odd too me at first- to toss newbies on a cutthroat server with full open pvp and limtied time span. But immediately I realized the benefits. Whether veteran or newbie- we are all the same! It's like playing an mmorpg at launch which is some of the most fun times for almost any mmorpg (besides the bugs). Normally in games like EVE Online, World of Warcraft, or what have you Guilds have requirements and criteria you must met before joining. Almost always it boils down to "Time". Well all of this is removed. It's all player skill and how much you want to win.
It's a persistant world though. You explore the universe, visit stations, run Quests (like taxi cab), and colonize worlds. You colonize worlds by finding a suitable planet to sustain a colony then dropping a bioglobe there. Then you go to space stations and find people that want to find a home. You grab these colonists and drop them off at a Colony that you own. The more colonists, the more money they make you even while you're offline sleeping!
It's not all roses. Begininers Galaxy is 100% open PVP. But here is the good news. Starport is all 100% player skill. You fire your own turrets and dodge fireballs yourself. So even if confronted by a veteran because your player skill is a factor, you can survive.
Did I mention there is no grinding for skills or levels? You can earn money to buy more weapons, more bioglobes, and better ships but its player skill that will determine victory first and foremost- the way PVP should be if you ask me.
All ships/items are viable here from what I've noticed. Newbie ships- the very first ship you get is the fastest ship in the game but has light damage. As you progress, you can purchase other ships.
Starport is a 100% persistant game on Begininer's Galaxy. Mind you I played on the hardcore server- so please no knee jerking here. Anyway, when you logout everything is still online. I mean everything. Your ship is still online, your colonies, your possessions, everything. It costs money to logout in the safe zone haha. The taxes are crazy. So most people I think park out in open PVP zones. You can build turrets and such to protect your planet and colonies.
This is where 'sleeper ganking' comes into play. If some clever theif makes it in, he can end your life. Doesnt matter if you were offline or playing with your kids or at work.... Doesnt matter. You better setup great defenses.
When you die, you lose your ship and you receive insurance. But your cargo and such is lootable. Your colonies can be stolen too. You can lose it all on the hardcore server fast. This is the strategy of the game- finding distant planets and setting up defenses to protect everything.
The community seemed really nice and mature. Since there are many different flavors (hardcore open PK and the other light server options I didnt even read about haha)- we all share common interests. IT's all wolves hunting wolves and very few tears. I vastly preferred this community over most bigger titles that had a huge range of people with totally different agendas. At least in this one- its all Lions fighting for control of the Jungle.
Sandbox like PVE. Sure, you can do "Quests" like escourting NPCs and such. But really I term this sort of PVE as "Sandbox PVE". Nothing is forced on you. If you feel like questing you can. If you want to explore, you can cash in big on discovering wormholes, rare resources, and awesome planets to setup a financial venture. You can also disocver enemy planets of course. And this is how PVE comes into play. PVE/PVP is blended together here cohesively. An enemy player can setup a Colony on a planet and logout. This is your time to strike. Thieves might try to sneak in and get the colony without destroying anything. But you can also use brute force and raze it all.
This is the beauty. When you takeover a planet its all yours. Now you can proceed to kill all the NPCs on that planet and they STAY DEAD. They wont come back once you take the planet and make it yours....
Anyway I know this sort of gameplay is not for everyone but it was a totally awesome MMO when I last played it. It's worth a try f you are burned out on the treadmill and need a break. Also recall I covered one server type here- the hardcore server which is highly populated. There are also persistant servers as well but I can only imagine Time plays a huge factor on those. Begininer's Galaxy is a great way to get your feet wet. The Limited timespan for the server really helps keep the playing field balanced.