It's tricky to play two MMO's, there's no doubt about it. However, it's a a very hard time finding cheap entertainment in this economy, and some times - you just get bored with one MMO. It happens. That doesn't mean you won't want to play it from time to time, or you won't want to raid with your guild on Tuesday evening any more - it just means you want another option. Makes sense. However, getting another MMO can be downright expensive - playing CO, AoC, War, Aion, CoH, STO, LotRO, and any number of others at the same time can cost you a rather large fortune. Luckily, you have other options!
1) Free to Play is your friend!
There are a number of free, yes, free MMOs out there. And even better - there are quite a few good ones - not just flash-based browser games like AdventureQuest or NeoPets that can scarcely call themselves MMOs, or things like... *shudders*... Runescape.
The thing about these free games is that basically all of them have microtransactions. Meaning, if you have a collector's habit of wanting to get every minipet or title, it'll probably end up being more expensive for you to play this than to open up a new account in AoC or EVE.
However, if you can stand not buying the newest sparklepony on the block, there are some pretty fun, good, decent games out there.
- Chronicles of Spellborn: Free to play for the moment, didn't have an extremely solid beginning, but is working its way back. Has an interesting combat system - otherwise, haven't gotten a chance to check it out.
- Runes of Magic: Despite being very good at blatantly destroying contests, Runes of Magic is an often-toted WoW Clone. A decent one, but very very similar to it nonetheless - if you're looking for more WoW, go for it; otherwise, you might want to try something new.
- Free Realms: Targeted for a younger audience than most multi-MMOers, it still deserves note as one of the most interesting MMOs to date, simply because it removed the 'requirement' of combat-based leveling from the MMORPG genre. With kart-racing, cooking, and exploration all being ways to level, along with about 6 or 7 other options, it is an interesting and refreshing take on the genre.
- Allods Online: A pretty cool looking sci-fantasy game with hints of that over-used 'WoW Clone' branding, still in beta and said to be released at some point this year. Check back on release - the graphics are, well, stunning. Not Aion, but still very cool.
- Torchlight Online: Still in production, but promising to be a very cool game if the dungeon-crawler it is preceded by, 'Torchlight', is any indication. Not much information other than it will be free to play and micro-transaction based.
- Almost forgot! Dungeons and Dragons Online, better known as DDO, is a game turned recently from pay-to-play to free. It's been around a while, meaning it already has a decent fanbase and a bit of history - not a thouroghly innovative game, but decent and, best of all, free.
2) 1-Time Purchases
Even if you only have, say, 15$ a month to spend on your MMO, you might still have money you normally spend on those other, single player games. While I'm not going to cover those here...because this post would encompass several small terabytes... I can tell you about those 1-purchase MMO's that you pay for once - then you're done.
- Guild Wars (plus like 5 expansions): Arenanet attempted to revolutionize the gaming subscription models with this game. They thought, hey, we can sell these games - no subscription attatched - just like any other game, and it could work if we sell enough! Cool! However, when it was released, people slowly began to realize that it wasn't an MMO at all. The entire world outside of cities was instanced - making it just a couple of visual chat rooms with solo or group games that you can play out of them. Still worth noting, because it can be a fun game.
- Guild Wars 2: They came back, 5 years later, reevaluated, reassessed, and decided that it was time to make a new MMO - same subscription model of a 1-time purchase (though a number of expansions) - however, in an actual virtual world. Coming out (probably) some time this year or next, definitely keep your eyes peeled for this one. Looks to be a very, very cool game.
- Global Agenda: This one's a bit tricky, and not necessarily an MMO persay, however I'd brand it one. However, the stuff that typically brands it as an MMO - crafting, end-game leveling, open world environment - only are unlockable with a (you guessed it) 15$ a month subscription.
3) Lifetime Subscriptions
The last... and the most difficult to suggest. Whereas you can pay 15$ a month until you want to stop, some MMOs nowadays are offering limited lifetime subscriptions for a fixed rate, until the game goes under. I urge caution for a few reasons with this category:
First, most MMOs offer this as a limited offer, only allowing you to purchase it before or within a few weeks of release. You might not know what you're getting in to.
Second, the world of MMOs is just that, a world, evolving an constantly changing. you never know when your game developer might pull a NGE on you and reverse your loved game into a graveyard overnight.
Third, the 'industry standard' for the cost of these is 200$ - and rising. This is pretty expensive, and if you play for a full year and two months you'll barely break even. If you plan on playing more, great, but otherwise... meh.
- Champions Online (Over) This is one to pay very close attention to if you're thinking about getting a lifetime subscription - apparently, Cryptic has released additional, important and almost necessary content to the game - for a price. Think like a full patch, a whole zone, held only for people who pay. Even the ones that shelled out the 200$ at launch. It's a bit sketchy.
- Star Trek Online (Over) This is one I got in on, however, we'll see how it works out. First off, it's a good 40$ over the standard price, and with the same people that made Champions Online. However, I have one explanation for why I bought it, despite all of this advice - I liked it. I liked the game. It was fun. Entertaining. A cool IP, with so much potential and even more interest. I don't see it as a WoW killer (stupid term, by the way) or anything, but I can see it being a fun game. Also, I know I won't be able to afford two accounts at the same time, so it makes sense to buy it now - when the value is constant and will thin with time.
- Lord of the Rings Online This one's 300$, but only after their own limited offer of the standard 200. However, it is available still, which is pretty neat and a great giveaway. However, with it being 3 years old, it is an odd choice to buy now, with a necessary 1 yr 8 months to break even.
In recap, there are a number of ways you could, and can, play multiple MMOs - without ever subscribing to a game, or just subscribing to one.