Gap works fine and always has a lot of people on the network. The original dev has a lot of gap that he/she bought, and so has not abandoned the project to the wind, but there hasn't been much activity. You are welcome to help develop the coin.

An explorer is at https://chainz.cryptoid.info/gap/ Its hosting expires soon and can be extended by donating any amount to 1M1sWXQ97kVx1Lk6SCVZvuTjt68od2MrVQ its $9.9 per month and seems to get extended bit by bit by generous people. When the coin goes up enough it will probably get extended a lot more.

As far as math coins, gap is better in some ways than riecoin and primecoin. Why it was removed from Poloniex I don't know.

Since there is a block explorer, no bounty for that, but if you want to do something useful, have some idea, mention it and somebody might offer a bounty bto you to do it. Gapcoin has avoided hype and pumpiness and sleazinesss so nobody is going to bounty a signature campaign or anything like that, but if you have a good idea say it.