Employee Engagement Activities - what kind of days will be celebrated and what kind of theme?

I am working in the Small scale IT company As a HR manager. As my Employees need some refreshment activities for fun and days celebration.
So what kind of days will be celebrated and what kind of theme of colour dress code can be done.
Request you all to Suggest me

Atleast you can start with Birthday Celebrations. Please revert with your experience to guide you further.

Hi ,
I have 2 years of experience and we do celebrate the birthdays of employees and also the few festivals

Hi,
Birthday/work anniversary must be celebrated with emails and cake cutting.
You can ask all employees to wear same dress code/colour or semi casuals on Fridays.
Try introducing 5 mins music and dance sessions early morning to kick start the day of the staff.
Thanks and Regards,
Akash Sharma

You may have an annual family day when employees with their families go on a trip, or engage in cultural/sports activities

You may have yearly dinner with music where all employees' from top to bottom attend the event and the communication barriers between hierarchy also reduced. It creates a positive culture because employees' feel that management cares about them.

Thanks everyone for your response