Pedestrians walking by two Calgary high-rise buildings are largely unaware of the battle raging 30 storeys overhead.

But this war is being fought with an unconventional weapon – Post-it notes.

Employees at oil and gas company Enerplus have adorned their office windows with an R2-D2, Wario and Pac-Man using Post-It notes.

"We're just waiting for them to retaliate," Enerplus employee Liza Rooprai told CTV Calgary on Tuesday.

She said the Post-it war started last month, when employees at a neighbouring building displayed their own Post-it creations.

The Calgary battle follows a highly-publicized Manhattan Post-it war, which ended with an epic mic drop late last month.

Rooprai said Enerplus's main rival removed the Post-it notes from their office windows on Tuesday, only for another office to jump into the fray.

She said Enerplus management has been supportive of the ongoing Post-it war as it’s boosting office morale.

"They're pretty excited that we're getting low-cost way of team building, given the current economy."

With a report from CTV Calgary's Bill Macfarlane