Let this disaster serve as a cautionary tale: what happens when you are greatly successful once, then cling to that while the world moves on?
The Halcyon is a LaserDisc-based machine from RDI Video Systems, the same company that made the LaserDisc-based arcade hits Dragon's Lair and Space Ace. Trouble is, the novelty of interactive movies was wearing thin, but RDI just didn't notice it. Nor they took in account that most kids don't have the same kind of budget as professional arcade operators. So they launched the most expensive video game console ever ($2500, or $5400 adjusted for inflation), designed around a kind of game that people didn't really care for, at a time when the gaming market had simply collapsed. To no one's surprise, RDI went bankrupt a few months later.
It was ambitious, you have to give them that: it even had voice synthesis and speech recognition. But RDI's quick demise meant it was left with a library of just two games: a lame American football one, and an interesting animated fantasy, Thayer's Quest. Now, as that was later released on other systems (aka Kingdom: The Far Reaches), you have no reason to get this console, unless you are a collector with a hard-on for obscure machines.