This is the XCOM: Ultimate Collection bundle but it's not on steamgifts. It includes:

XCOM: Enemy Unknown
XCOM: Enemy Within
XCOM: Enemy Unknown - Slingshot Pack
XCOM 2
XCOM 2: War of the Chosen
XCOM 2: War of the Chosen - Tactical Legacy Pack
XCOM 2: Resistance Warrior Pack
XCOM 2: Anarchy's Children
XCOM 2: Alien Hunters
XCOM 2: Shen's Last Gift
XCOM: Chimera Squad

Best of luck.