Printed items everywhere on walls, tables, etc. should include a good variety such as tickets, timetables, schedules, ads, labels, and announcements. Find unusual items. Large black and white photos or pictures strung across the room on a line with black or white clothespins add a darkroom effect. Pass out pencils and small notebooks. Have the guests list how many different kinds of printed items they saw since they arrived.
Most correct answers win.
Previous to the party, ask folks to collect an assortment of dials from no longer used appliances etc. Tape a number on each dial and keep a numbered list of answers. Guests need to identify as many dials as possible. Make it difficult. Divide guests into one black team, one white.