The local playground offers many opportunities to work your body hard. The fundamentals of the playground provide lots of different climbing, pulling and pushing apparatus along with various bench platforms as well.
So here is a playground workout designed to get the heart rate racing and the muscles pumped up.
Bench jump ups
Find a park bench or playground platform. Perform 10 jump ups driving through your quadriceps during the movement. Squat low before the jump to initiate the drive. Keep this action powerful. Either step back down off the bench or jump back down to the starting position.
Dips
Find yourself some parallel bars evenly spaced. Support your body weight at the top of the movement then lower yourself down by bending at the elbows. Stop at a 90 degree bend at the elbows then return to the starting position. 10 repetitions or go to failure.
Do bench dips if this movement is too difficult.
Hanging Leg Raises
Hang from a parallel bar and hold feet and knees tight together. Lift your legs up straight till you reach a parallel angle with them. Pause briefly at the top of the movement then under control slowly lower legs to the starting position.
10 repetitions for this one or till failure.
If this is too hard try bent knee raises instead.
Chin Up
Using a parallel bar, grip the bar just outside of shoulder width apart. Fully stretched out, pull yourself up till your chin is above the bar. Then return to the starting position.
10 repetitions or till failure.
Decline Push Up
With your feet raised on a bench or platform, perform a push up by lowering your chest towards the ground then return to the starting position. By having your feet raised makes this movement slightly harder than your traditional push up.
10 repetitions or more depending on your fitness level.
Inverted Pull Up
Find a lower bar or cable as in this case. Lying under the cable with your arms supporting your body which is in a straight plank position, pull up yourself up till your chest touches the cable then slowly return to the starting position. This is a good movement for those who are unable to perform many chin ups or pull ups as an alternative exercise.
10 repetitions.
Swing Chest Flyes
Using 2 swings of even height, grab one in each hand. Lean into the swings with your arms close together, as in the image. Slowly widen your arm span stretching out the chest. Go no more than parallel with your arms, then squeezing through the chest, return to the start position.
Aim for 10 repetitions.
Swing Jack Knife
In a push up position, have your feet raised on the swing. Curl your feet in by bending at the knees into a tucked position. Then control yourself back to the starting point.
Aim for 10 repetitions.
Swing Single Leg Lunge
Back foot raised on the swing and front foot on the ground; slowly lower your back leg knee towards the ground. Feel a good stretch out through the hip then gradually return to the starting position. By having your foot on the swing creates an unstable environment thus working all your supporting structures of the knee.
Swing Leg Curls
Similar to swiss ball leg curl except using the swing.
Lying flat on the ground feet raised on swing. Your body should be in a plank position from shoulders to toes; flat and rigid. Curl your legs towards your buttocks, hold, then return to the start position.
Aim for 10 repetitions.
This is a very basic workout focusing on all the major muscle groups of the body.
Every playground is different so get creative and see what you can come up with.
The world is your gym, get amongst it! 
Karl