If all you're going to play is casual games, you'll be OK with an All-in-one.
Some All-in-ones actually have video card chipsets like the Geforce GTX 1050 that could play more demanding genres as well as casual games. For example some of the 24" All-in-ones at https://www.dell.com/en-us/shop/del...5000-all-in-one/spd/inspiron-24-5477-aio
have the Geforce GTX 1050 with 4 GB of dedicated graphics RAM.
I haven't seen games running with the integrated Intel graphics 630 graphics.
It would probably be OK for casual games even though it has no dedicated memory.
What size screen were you looking for? Dell has 22", 24", and 27" sizes.
The 22" seems to be the cheapest, but they only have 4 GB of system RAM so I wouldn't recommend them. People have reported slowdowns just browsing the Internet when their computer only has 4 GB of system RAM. So I'd recommend getting a computer with at least 8 GB of system RAM.
Some of the All-in-ones at Dell only have a small size 128GB or 256 GB SSD drive, while others have an additional 1 TB hard drive for storage. Considering that I've filled up a 320 GB drive with my Big Fish games (and had to uninstall some of them), I'd recommend getting a computer that has the extra storage.
Some older casual games don't seem to work with Windows 10.
Most should work, though some may require tweaks like running as Administrator.