Generally, when it comes to .io games, simpler is better. Slither.io has you playing as a snake, trying to increase your length as much as possible. This is accomplished by picking up glowing dots, the largest of which are created from killing another player's snake.
The ingenuity of Slither.io comes from this interaction -- the only way to kill another snake is to get it to run into your side, and the only tool assisting you is a boost ability you can use at the cost of some length. Pulling off the maneuver is far easier said than done, and getting good at the mind games involved is a large part of the game's appeal.
The best part is that if you luck out, there's nothing stopping you from killing a snake much larger than you are.