There’s no definitive list of what is or isn’t personal data, so it all comes down to properly interpreting the GDPR’s definition:
‘[P]ersonal data’ means any information relating to an identified or identifiable natural person (‘data subject’). — Article 4(1)
In other words, any information that is clearly about a particular person. But just how broadly does this apply? The GDPR clarifies:
[A]n identifiable natural person is one who can be identified, directly or indirectly, in particular by reference to an identifier such as a name, an identification number, location data, an online identifier or to one or more factors specific to the physical, physiological, genetic, mental, economic, cultural or social identity of that natural person. — Article 4(1)
This means that because you say that coordinates and anticheat logs are linked to the cheaters ingame username and unique id, if there is a record of who that username and/or unique id belongs to, even if it is just an IP or email address, it is considered personal data because the information relates to an identifiable natural person.
Personal data includes any data which can be linked to information where a person can be identified
From Comments
If the online username and unique id is not linked to the actual human (no stored real name, no home address, no IP), can the natural person actually be identified? The records and anticheat logs are linked to the unique id and username, however the unique id and username are (from my POV) not actually linked to the real human
Only you can answer that question as it stands because we have no access to your data.
From what you have told us, even though the coordinates and anticheat logs are linked to the cheaters ingame username and unique id, that alone doesn’t fall under the GDPR’s scope of personal data, as, in all likelihood, the usename and unique id could relate to anyone in the world. The issue comes if elsewhere you have a record of the person's name, IP, date of birth etc. which when combined with the anticheat logs could link that data to identifiable people.
You might think that someone’s name is always personal data, but it’s not that simple, as the UK’s Information Commissioner’s Office document what is personal data (PDF) explains:
“By itself the name John Smith may not always be personal data because there are many individuals with that name. However, where the name is combined with other information (such as an address, a place of work, or a telephone number) this will usually be sufficient to clearly identify one individual.”
Note: A name which is much less common could be personal data as the likelihood of it relating to others deminishes. John Smith is a common name all over the UK, but what about a particular polish/czech/hungarian/french.... name (let's say) living in Nottingham, UK? What is the likelihood of another person of the same name in Nottingham, UK? Add a middle name or double barrelled surname, and it becomes even more likely that it is personal data.
If you’re unsure whether the information you store is personal data or not, it’s best to err on the side of caution. This means making sure data is secure, reducing the amount of data you store, collecting only as much data as necessary to complete your processing activities, keeping data for only as long as it meets its purpose, and ensuring only authorised people are able to access the data.
