The online game (www.redcross.org.uk/firstaid) forms part of an above-the-line drive, which includes outdoor media.
More than 3,000 people are killed each year on UK roads and the charity aims to reduce this by teaching people first-aid skills in just five minutes.
Outdoor billboards, with creative by DFGW, use images of floral tributes left at the scene of traffic accidents.
Initial posters reading 'Cut flowers. 3,221 people died on the roads last year' have been positioned along major traffic routes in the UK.
The final poster design reads 'Cut flowers. Reduce road deaths. Learn to save a life in five minutes at redcross.org.uk/firstaid.'
The online game, accessible on the BRC homepage, mixes stylised photography and illustrations, backed by an original soundtrack. It presents players with a series of challenges, which they must face to save a young girl who has been involved in a road accident.
The game, created by agency Atticmedia, is being promoted in the BRC monthly newsletter.
Earlier this year, the charity hired branding agency Loewy to raise the profile of its own-brand first-aid training service. It was charged with developing all marketing material, including online banners, brochures and ads for the business press.