A land restriction may block a proposed playground in West Haven memorializing the 20 children and six educators who were fatally shot at Sandy Hook Elementary School. Twenty-six ‘‘Where Angels Play’’ playgrounds are being built by the New Jersey-based Sandy Ground Project in Connecticut, New Jersey, and New York. The New Haven Register reported that the West Haven Land Trust has a conservation easement intended to shield the shoreline from development, which could include a playground. Trust members worry that approving a playground would set a precedent. But Mayor Ed O’Brien and other city officials said West Haven will look heartless and disrespectful if it rejects a proposal to honor the victims.