If I were a game developer and my game would be online, or would have an online mode, I would not want people to use trainers, as it could potentially ruin the game for others, so my answer to your question is no, it is not safe.
If you mean valve games, probaly not safe they are ussually vac-secured
It just strikes me as odd to have enforced/automatic online scoring in single player PC games when trainers are so easy to get, even if people have no interest in doing it for the ranking.
[Edited by AG3, 1/19/2019 5:16:58 AM]
Oh, my bad friend. I misunderstood, my apologies. It should be safe to stay online, as long as the game is only singleplayer there is nothing you should be scared about, at least I don't believe so, because I did use trainers in SP games while I was online on Steam.
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