Opening Ceremony - Best decorated Bank wins - each team picks a country out of the hat to represent and decorates their bank to that theme.
100m RC Race - Using 1 or 2 remote controlled cars race around a predefined course in the office, top 3 fastest times win
Discus Hoopla - Using the hoopla set 3 highest scores win. (in the event of a tie there will be a hoopla off)
Paper Aeroplane Javelin - Each team must create a paper plane made only of paper A3 or smaller. Nominated person stands on the line and furthest planes win
Archery - Throwing paper balls into waste paper baskets at different distances top 3 win
Synchronised office chair swivel - (my favourite) Needs no real introduction just someone/people to judge
RC Long Jump - Furthest jump in a RC car on a home made ramp
Shooting - If you have whiteboards you can use the toy guns that shoot the sticky bullets, these work very well on whiteboards.
Boxing & Volley Ball - You would need a WII or X Box for this.
Table Tennis - You can by a set online which gives you a net, 3 balls and two bats that you can use on a normal office table, got mine for £2.49
Triathlon - A combination of 3 events, starting with the 100m RC race, followed by 10ft Shooting and finished with Bin archery.
Rock, Paper, Scissors judo - explains itself.
Hope these help and i would welcome other suggestions for some fun office safe game ideas.