I recently picked up this game to clear the set on RetroAchievements. It’s an incredibly straightforward experience, honestly, there isn't a whole lot to it, but it’s worth breaking down how it actually plays since it’s surprisingly functional for its age.

The good

• The graphics are simple but distinct. Given the limitations of the SG-1000 hardware, the sprites look pretty good. The characters have a very "cartoony" vibe, but they clearly look like people, which is more than you can say for a lot of sports games from 1984.
• One of the most surprising things is that the hitboxes are actually well-made. The AI can’t just "ignore" your punches; once their invincibility frames end (about half a second after they throw a punch), they are fair game. It’s refreshing to play an early fighter where the computer doesn't blatantly cheat.

• The AI acts more like a human player than a script. It’s essentially as good as you are, just with faster reaction times at higher levels. It makes mistakes, whiffs its shots, and will actually try to back away and "run" if you get too aggressive. It feels like a genuine back-and-forth rather than fighting a brick wall.

The bad

• There's only one opponent, the same guy, the levels just make him faster.
• The game has a pretty hilarious exploit that breaks the difficulty. If you time a punch just a few frames before the opponent attacks, they get stuck in a "hit-stun" softlock. You can just keep combo-ing them, and they can’t block or counter. Just be careful, the AI can do the exact same thing to you.
• There's no music, just you, the ring and the opponent. The only music is at the title screen and the victory fanfare.

Conclusion

It lacks the polish and personality of something like Punch-Out!!, but for a 1984 home console title, it offers a fair, if repetitive, challenge that doesn't rely on "cheating" AI to provide difficulty.