Just go to the 'contact' button if they have a website, or check Whois to see who owns that name. A 'Hey, I have npgamers.com for sale; you guys want to buy it for a very reasonable price?' line, short, friendly, direct, and especially with the 'very reasonable price' tipped in, will work if they're at all open to buying this name from you.
If they're not, or won't give you a price you feel you can't do without, then you're back to slogging away at marketing your name to the big bad world, like the rest of us.
Developing more will ALWAYS increase the attractiveness to buying a name. Even if your traffic isn't making you money on the site, an interested and canny domainer can usually tweak things, with traffic already coming in, to make some income out of it. Very attractive if you have a pre-existing traffic flow to a domain, not only for income possibilities but also to anyone who likes your site and may want to keep it running as-is, if that's a possibility.