1. Tell famous people / youtubers to play the game in a hope to bring many new players
It could work, but maybe it would only last for minimum a week or at least a month. Because the reason why people would visit & play the game is just because to be able to meet or see the famous people / youtubers in it, or get inspired by them to play the game. Come to think of it, i'm curious on how the youtubers reaction if they play this game (Which still had un-solved issues in it. Like Lags, bad quality servers, current PP system, toxic players, etc)
2. Advertise the game in other sections of the Internet
I have try best to do this for the past months, like telling friends & other people at other online games to visit & play PB2. Some only play as guest, while some do have register (which i help at discord on how to make an account...) but most tend to play for a short while, And goes offline in less then a week. Due of either bored or not enjoying the gameplay due of certain common issues in PB2 multiplayer (Especially due of toxic players behaviour...)
The best way that i can think of right now is someone that is creative to make an official ads for the upcoming PB2.5 & PB3, and publish it in the whole internet. The result : Gain money & create a curiosity for people to come & play the game. Just like World of Tanks & other popular gaming ads.
3. Make an animations for PB2 series and upload it on Youtube
That would be great idea. I seen Minecraft animations, FNAF animations, Undertale animations, Bendy animations, & other famous animation game videos. They been seen by a lot of viewers, which create millions of views & likes. Especially if it's involve a original - parody song videos. As a matter of fact, i actually try to learn to make animations myself. It's going to take me a long time to fully understand it, as i'm still busy at school & almost go to college someday. But sooner or later eventually (maybe...)
Like imagine a Plazma Burst animation movie video, or even a PB2 song videos. xD
That's all i have to say at this point. Correct me if i'm wrong ~ Regards