Strategy

All game modes

Virus tactics

Find an area with three close viruses. Stay there for a while and wait for big players to pass. Split them using eject function, and then do something strange; don't eat them, eat the players that come to eat them. You will gain more mass this way.
If you are around 200 mass and have cornered a 100 mass player in a virus, here is a simple trick to eat them; split twice into them. They will eat one of your pieces, and become too big and pop on the virus. Sometimes you may even absorb all their small pieces entirely. If not, you can split kill them. This is known as a mini popsplit.
When shooting a virus, always make sure they will
- Be hit by it;
- Be close enough so you can eat some and
- Make CERTAIN you have enough mass to fire, and still be big enough to split for the small pieces afterwards (~300 for a fresh virus) If you don't, you will almost be as small as a newly spawned player and for nothing.
You can hide in viruses and wait. Wait until someone comes dangerously close to you, then quickly get out and eat them or wait a little bit longer until someone smaller than you thinks that the virus you're in is empty but in reality they just got eaten and killed. If you eat a player that brings you to over ~120 mass, move out of the virus IMMEDIATELY!!! If you get any bigger, you will ultimately split to death.
Find a perfect small virus, have a mass of 120 and make sure no one saw you in the virus. Players only see you as a cell but not the virus and looks like you are "away from keyboard". Then when a larger mass comes to eat you like any other cell does to "away from keyboard's", quickly get back and the player explodes.
Split onto a virus. After that, keep on eating other viruses. You will not split more as long as you don't combine.

Strategy by mass

When you are small (10 - 120 mass), just eat the ever - spawning pellets. It is OK to go into the viruses temporarily to escape larger players, but do not use it as a strategy.

When you are medium-small (121 - 280), you should start eating smaller players. It is a bad idea trying to hide in a virus as you will get split.

When you are medium (281 - 500), you should start trying to team or shoot viruses into larger players. Now you can (probably) accept the W pellets that players use to lure smaller players as you might be too big for them to split on you. Beware that many giant players use the blob-luring technique.

When you are large (501 - 1000), you can use the blob-luring technique too. Beware that smaller players might shoot viruses into you now.

When you are giant (1001 - 10000), you will start losing mass quickly, forcing you to eat smaller players. You can split into a virus and wait for a small player to eat your smaller cells. Once a player comes, split and eat them.

If you are larger than this (10001 and greater), you may be forced to stay in a small spot as viruses will block your path. You should just eat the viruses (after you have already split into 16 cells), as many players will not be able to eat your larger pieces.

Split tactics

There are three fundamental rules to splitting.
- Never split unless you are sure no viruses or big players are ahead.
- Be sure that you know you are at least 167% bigger than they are before splitting. You need 33% more mass to eat them when split.
- Be sure you are splitting for someone worth it. Small cells are tough targets and a risky choice.
When you get to 35 mass, split IMMEDIATELY. This way, you'll have a significantly larger view, a wider area for collecting pellets, and a higher speed.
If you're sure there are no larger players around and you find a rich field of small dots, you can split once or twice to decrease your mass, increase your speed and surface area to more quickly "eat" the dots in the rich field to gain mass. As you eat more, your parts will begin to re-coalesce. Occasionally this can be dangerous, if a larger player stumbles upon you, as you will be more edible and they may split to consume your smaller parts. On the plus side, you're smaller can can often "get away" by outrunning them.

General Survival Tactics

If you are bigger than someone but are split in half, find a wall and W key until you have a microcell and a huge cell. You can easily afford to lose that tiny cell, and will scare off most enemies. (BEWARE: Only 14 out of the 16 mass in ejections are absorbed, so use this sparingly!)
If you're about to be mowed down by a larger player or mob of larger players and don't want to die, split in order to decrease the mass of both / all parts to get away with at least some of your mass intact. Sometimes, you can even get away with all of your mass intact, albeit in smaller pieces. Once you get away, find a rich source of tiny cells to eat and grow or eat until you merge.
Sometimes you will be chased by an opponent your size or slightly larger. Just stay ahead of them and find dots to consume. Since you're in the lead, smaller and can stay ahead of them, you'll eat the dots and grow in size to their size or larger, at which point they'll usually break off and leave you alone.
Risky survival: If you're being chased by a larger opponent, and chased toward other large(r) players, you can sometimes survive by keeping equal distance between them, but risking getting slightly close to the larger player, since the smaller of the two larger players will not want to risk being eaten by the much larger player if 1) they get too close or 2) they split to eat you, but their parts become small enough for the larger or equally sized opponent to then eat. This can sometimes backfire if the larger player decides you're a worthwhile meal, splits, eats you, and goes after the slightly smaller larger opponent after that piece grows due to eating you. But this does work about 1/3 to 1/2 of the time as a last resort when you're being overrun by larger player(s).
If you have between 130 and 300 mass, you can feed a virus and hide in it for survival. Only do this when absolutely necessary. Do note that others can still shoot the virus and you will pop, or they can still mini popsplit you.

Social tactics

You never want to be #10 on the leaderboard. Why? You will be a target for the big leaderboard players who have almost none worth eating. Also, your name will be given away so future enemies know to target you as you are near-board size.
1. Don't impersonate YouTubers. This leads to the YouTuber in question being forced to use different names. Don't impersonate the names that the YouTubers use in their videos as well.

FFA/Experimental

Find a Spawner Cell and feed your spawner cell then your spawner cell immediately becomes bigger and then eat the mass your cell dispenses and scare away hungry bandits that want to eat the pellets the cell dispenses!
when your very big like 12K+ mass split 16 times and eat the spawner viruses they give 200 mass and also you don’t split eating them when split into sixteenths.

Teams

Stay near a big player, and try to receive mass that is either split. Another idea is to build mass, and split other players. This institutes a high variety of split cells that can easily be consumed.

Party

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Battle Royale

In a Battle Royale, usually, around 20 to 40 players are put on a server to see who can survive the longest. Players are forced to stay in the safe area as it shrinks. Going into the red area or hazard area will split and shrink any cell until it completely disappears. Players must eat mass to grow bigger while watching out for opposing cells. Once eaten, players are forced to leave the server, but can still spectate. As the safe area shrinks, players are forced to move closer to each other, making survival riskier.

A player’s cell should be in one piece near the end of the match. Also, a mass of around 300 will allow the entire safe area to be visible. Only shoot viruses if the targeted player is directly in front of or almost on it as it will result in quick mass loss. Make sure to be the smaller cell when directly on another player. So, when the safe area shrinks, the opposing cell will hit the hazard first. Good Luck!