"Bill Witts wrote this as his first non-trivial Java program back in 1996 as a challenge to write BattleZone, the once well-known Atari arcade game, in 24 hours. In the end, it took 32 hours. Bill wrote the original Atari-approved Quicksilva BattleZone game for the Sinclair ZX Spectrum back in 1983-84, and it took perhaps 15 months in total, so this is a quite favorable comparison of Java versus Z80 machine code (although it helps that your computer is probably 2-3 orders of magnitude faster than a Spectrum...)."
The ancient arcade game BattleZone playable through a web browser.
I like that "it helps that your computer is 2-3 orders of magnitude faster than a Spectrum...". Probably more than 1000 times faster, actually.