Apokalipsa is a memory resident parasitic virus. It hooks INT 21h and writes itself to the end of .EXE files that are executed.
After year 2000, the virus decrypts and displays the messages:
Wellcome to 21st century. Author (Martin Zdila - MATOSoft) wish you no viruses in your computer (except me - APOKALIPSA). I (virus) was born in SLOVAKIA in 1997/98. Don't panic, I am harmless virus what is waiting for APOKALIPSA. Press any key to continue. Oh my God ...APOKALIPSA is here !!! ALL DATA ON YOUR DISK ARE DESTROYED, FOREVER ! ... ha ha ha. I got you! Great joke, isn't it ?!
Securelist (Kaspersky Labs), Virus.DOS.Apokalipsa.1167