It may be a new.io game but it has managed to become quite popular among online players. It is basically a game where you travel around a map as a piece of paper with expanding territory being your major goal. A paper trail maps out your territory as you move around and you will also need to defend it from other players. Lots of attention is required to be a success when playing the game considering that your paper moves automatically when you spawn and this increases chances of it running into other players of even walls. The direction you move to is of utmost importance, but there are so many other things you need to keep in mind to make play time more enjoyable and rewarding.
Increase your area with care - Remember that running into your trail will leave you dead and for that you need to be close attention, especially when circling back in order to connect again with the area to increase it. You may have an easier time working out the trail away from the territory and then circling back careful to connect and make the increase.
Learn to play safe - When playing paperio, treat opponents as vultures waiting for a chance to break your trail. Stick out a bit when making the trail but be ready for other to dash right at you. It is best that you try to target small parts of the game board at a time compared to overextending which risks your area being broken by others. The further away you are, the higher your vulnerability; keep close to your base so it is easier to make safe zones every time.
Be a defensive player - Apart from going out to make your trail as a way of expanding, you have the options of lying in wait till opponents make their move. As they foolishly slither to your base you can make a killing. Taking them out as they infiltrate your base as you lie in wait is fast and easy as they have no protection whatsoever.
Identify spawn points - Being near spawn areas means that it is easy for others to pull a fast move on you when you least expect. Considering that most of the spawn points in slither.io are random, you need to be extra careful when claiming new space. They could be near your base or right in front of you.