I do not know the nature of your business/company. Anyways, I suggest the following initiatives you may use as suitable.
1. Email Game - You may post some interesting questions in the email and award the first correct answer.
2. Fun Hour Every Month - Conduct some fun outdoor games every month for about 2 hours. Plan for refreshments, take photos, display them on your notice board, and spread happiness.
3. You can sponsor a dinner (excluding cocktails) for each department once a year.
4. Form sports teams based on employees' interests and encourage them to play after working hours. Ensure you provide necessary resources.
5. Conduct a sports day once a year.
6. Celebrate employees' birthdays and display their photos in prominent locations.
7. Send childhood pictures of key persons in your organization and have employees guess the person.
8. Create a play station and keep it open during the lunch hour.
These are my suggestions; implementation depends on the nature of your workforce and the management's interests.
All the best! Have fun!
Regards,
M. Ramya
HR