Acyd is a game similar to agar.io however it is based in space and you take control of a moon consuming stars/other players in order to dominate the game. This game can be quite tricky at the start as the movement is quite a bit different to other games like this, I will cover the controls specifically at the bottom but you travel in the direction opposite from your cursor so it can be puzzling initially.
Acyd.io is pretty simple to get a grasp on, you wonder around space as a moon consuming mass and aim to get bigger than anyone else, initially you can choose between 5 different shapes although this is purely cosmetic, they do not give any advantages/disadvantages. Initially following some of the bigger players can be advantageous as the mass they drop off will increase your size significantly more than the smaller food orbs although be careful they do not turn on you! Eater stars are always a good option for gaining size but there are a lot fewer of them around the map so its good to get a mixed diet including other players!
The controls are a little different to other similar games, you use the W button to release mass in the direction that your mouse is pointing, doing so will thrust you in the opposite direction for example; boosting downwards would shoot you upwards.