You can always advertise the old fashioned way, and buy ads in traditional outlets like:

• TV
• Radio
• Print
• Outdoor billboards
• Transit (buses, subways, etc.)
• Direct mail

Before you say you can’t afford it, remember that all of these channels offer many tiers of pricing.  You don’t have to run a national primetime campaign to get on TV.  Sure, the audience is smaller, and so is the pricetag.  And if you can get an acquisition cost lower than your lifetime value, go for it!  Remember, if your game has a high virality factor (like it should) then being a big fish in a really, really small pond may be just the way to get the first bite.