Malware authors know that if they brick your PC immediately, you will format the drive and never use the site again. Instead, they deploy "time bombs" or "sleepers." You play Space Engine for two weeks. It runs beautifully. You disable your antivirus. You tell your friends it's safe.

For a safe and legal experience, supporting the developers by purchasing the official version on Steam is highly recommended. The official version guarantees safety, automatic updates, multiplayer support (if applicable), and mod support.