On one of our previous trip back to Singapore, we took an AirAsia flight that operates out of Singapore Changi Airport Terminal 1. We were feeling quite hungry after going around for half an hour stopping here and there accommodating the kids request to take pictures since it was Christmas time and Changi Airport was brightly decorated for the season. We had passed Burger King and didn't really want to detour, so we asked the information desk and was told that there is another halal fast food chain called "Texas Chicken" @ T1 Departure Transit Lounge.
Texas Chicken is at Level 3, D5, take the lift between Hermes and Bally and you will find the halal fast food restaurant. Texac Chicken serves average burgers and fries but hey, it's fresh and it satisfied our hunger :)
There is also a 24Hr Food Gallery besides Texas Chicken but I didn't check whether there are any halal-certified stalls there.
We were also trying to find an indoor playground for the kids at T1 transit hall but it was still under construction at that point in time. The indoor playground at T1 is just beside the outdoor garden. The outdoor garden though sounds nice still is not a "garden" yet, I seriously hope the people behind it puts more effort in making it a blooming garden that serves as a breathe of fresh air from the aircon surrounding. At this moment it is very bare.