NateG
EMAIL LISTS
When I first launched I had two email lists I used. The first was an email list I had laying around from an older game I had created many years prior. The second email list I stumbled upon for an old game with some similar mechanics to the game I was creating. I composed two sets of emails and sent them out to the lists. For the list of my old players I re-introduced myself and told them about the game. For the second list I started the email off with a sentence that said something along the lines of "this is a one time email, I will not email you again unsolicited. You are receiving this email because you may be interested in a game I've just created...". Those two emails got me my first 200 players.
ONLINE FORUMS
After that I found some gaming forums and asked the mods if it would be ok if I posted a message about Pit of War and they were cool about it and said go ahead. That style of marketing grew the player base again. I had a friend who was the mod for a high traffic web master forum and he made a post in their "off topic" section that helped get some more traction.
He also knew a handful of folks with a good number of Twitter followers and asked them if they'd make a tweet about Pit of War and they were kind of enough to do that for free to help me out.
PAID ADS
I tried Facebook ads a number of years ago and they weren't very effective, however, I'm told they are much better now. I may try them again in the near future. I then turned to cpmstar which is an ad network dedicated to games. This proved to be very good with the CPA (Cost per Action - which in my case is someone clicking on the ad and then signing up for the game) being much lower than the LTV for a player gained through this channel so I focused on that for awhile. CPA prices have gone up a lot since I started and there are many more games out there competing for the same eyeballs so this channel has started to wane but is still acceptable.
DEVIANTART & FACEBOOK
Using DeviantArt and Facebook I would upload some of the art from the game which would get shares and more eyeballs which helped increase exposure and player count.
WORD OF MOUTH
I asked my friends and family to try the game out and if they liked it to please share it with people they think might like it as well.
Hard to pick a best because each channel contributed. Having said that, the initial email lists and paid advertising via cpmstar were crucial for the success of the game I believe.
I run a small indie studio and our game Pit of War[1] is a very niche game (a PvP, character building, gladiatorial strategy game with text and still images. You don't get much more niche than that!) and we've found great success by managing our resources well and not chasing the latest craze be it flash, facebook, mobile, or what have you. We chose to keep the game on the web and keep full control over it instead of having to pass a judgment committee, or handing over 30% of our revenue to some platform. I found a niche that I enjoyed and had little competition and then built a game and a community around it. That last part is critical these days. I'm sure many of you have heard about "A 1000 true fans"[2], and it very much applies here. If you are using a F2P business model it is your bread and butter.
In 2010-2012 everything was awesome and then something happened in late 2012, early 2013. The user acquisition costs skyrocketed. In the last five years I've seen CPA costs increase 300%-600%. I spent time in Japan and knew some people at an ad agency there that mainly caters to mobile game companies and the CPA on those networks was averaging 700-800 yen (about $7-$8), with peak prices hitting 5,000 yen ($50) when Japanese companies paid out the yearly bonuses to their employees. Five years earlier CPAs were around $1.50 and less. The price increases on their networks have mainly been fueled by four or five companies like Supercell, GREE, DeNA etc. This is where the fairytale ended for a lot of indies and small studios hoping to make a living. It is a rare game that can pay those kinds of marketing costs and remain profitable.
My recommendation to anyone looking to get into indie game development would be to find a niche you enjoy and be the best in it. Build a community around it. Learn how to utilize an ethical F2P business model and last but certainly not least, have fun.
[1] If you are curious about what can be accomplished with a web based niche game you can check it out here: http://www.pitofwar.com
Regarding long work hours and terrible pay, not all employers are created equal. I eventually worked for a couple of different AAA companies before going indie and I had a very good salary and benefits at both companies surrounding by extremely talented developers. I have a few friends who I would say have extraordinary salaries and perks, however, they are very good at what they do. I have worked the crazy crunch times sure, but I think that is becoming less common especially after the EA Spouse debacle and the industry matures. It does still exist at some companies, however, there are many other jobs and industries out there that are just as demanding. I eventually went the indie route mainly just to see if I had the chops to run a small company and be the captain of my own ship. It was a question I wanted to answer for my own personal growth.
Working at a game company just so you can have a "job" is probably not a good idea. Just like I wouldn't recommend starting or joining a startup unless your heart is really into it and you love what you are doing because, yeah, there are going to be some long hours sometimes and there is a good chance you could be making more money elsewhere. If you like games, want to make games and are passionate about it, there are good companies out there that will pay and treat you well. Seek them out.
The game's forum uses advertising but the income is negligible, maybe around $10 per month. This is likely due to the fact that it is the same eyeballs looking at the ads and it is not a high traffic forum.