The game is designed to show how hard it is under ‘normal’ circumstances for a sperm cell to reach and fertilise an egg cell. The idea is to race your sperm through the giant female reproductive tract to reach the egg and win.

Sperm are recognised by the female as foreign and her body fights the sperm off as it tries to reach and fertilise the egg. The sperm face several obstacles along the way, including:

1. The vagina is very acidic and the acid can kill a sperm in seconds.

2.The cervix is full of white blood cells that attack sperm because they recognise the cells as foreign

3. The uterus is an extremely large area to a sperm cell, and many sperm get lost in this area. Only certain sperm are allowed passage into the fallopian tube

4. There are two fallopian tubes, but (usually) only one egg. Sperm are attracted to the correct tube by chemicals released from the egg.

5. Untreated Chlamydia infections can lead to infertility. The infection can cause scar tissue to build up and block fallopian tubes. This blocks the sperm from reaching an egg.