I have never heard about the title Terresterial Encounter so I gave it a go.

We have a vintage 1986 platform game here that reminds me about Jet Set Willy or Manic Miner. The jumping sound is strikingly similar.

The player guides a little astronaut around the screen to collect some keys, jump over enemies and obstacles. During this, the air supply is running out. I don't know if there are refills or if this is some sort of time limit per screen.

The sound is limited to very simple speaker-like YM effects and the graphics look pretty ugly, probably coder's style.

The game otherwise is fluent and does not flicker. I detected a TOS incompatibility with Hatari, the joystick does not work with TOS 1.62 and STE settings, probably all TOSes newer than 1.0 won't. The game works with 512k and TOS 1.0 setting, 1986 vintage style.

If it is a PD effort, I'd say ugly but not too bad. If this was a commercial game, it must have been a joke or people really thought 8bit style software was sufficient.