Hard Hat
Platform: Intellivision
Region: USA
Media: Cartridge
Controller: INTV
Genre: Action 
Gametype: Prototype
Release Year: 1979
Developer: Mattel
Publisher: Mattel
Players: 1
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Bill, Keith and Andy proposed the Party Line as a series of six cartridges, each sold separately. From their presentation:

Each team is building a skyscraper. Between the two structures hangs a platform stacked with bricks. Players must grab bricks for their building without upsetting the platform. Each team can slow down the other -- or themselves, if they're not careful -- by throwing the platform off balance. First team to complete their skyscraper wins.

Hard Hat was sent to the French office for programming (in the finished game, bricks were changed to panes of glass which could be knocked off of your opponent's building with a very satisfying crash). Julie Hoshizaki (Thin Ice) did Space Cadet.

http://intellivisionlives.com/bluesky/games/credits/1984b.html#party_line