adding multiple foreign keys to existing tables - sql

Question

I'm relatively new to SQL. I was wondering how I would go about adding data to my foreign keys. I have gotten errors with everything I've tried and google hasn't been much help... also, please ignore the nonsense data I've added.
Thank you!
Here's what I'm starting with:
CREATE TABLE GAME
(
GAME_ID INT NOT NULL AUTO_INCREMENT,
GAME_NAME VARCHAR(20) NOT NULL,
PLATFORM_ID INT NOT NULL,
PUBLISHER_ID INT NOT NULL,
DEV_ID INT NOT NULL,
GAME_GENRE VARCHAR(20),
PRIMARY KEY(GAME_ID)
);
CREATE TABLE DEVELOPER
(
DEV_ID INT NOT NULL AUTO_INCREMENT,
DEV_NAME VARCHAR(20) NOT NULL,
DEV_CIY VARCHAR(20),
DEV_COUNTRY VARCHAR(20),
DEV_CEO VARCHAR(20),
DEV_GAMES INT,
PRIMARY KEY(DEV_ID)
);
CREATE TABLE PUBLISHER
(
PUBLISHER_ID INT NOT NULL AUTO_INCREMENT,
PUBLISHER_NAME VARCHAR(20) NOT NULL,
DEV_ID INT NOT NULL,
PUBLISHER_CEO VARCHAR(20),
PUBLISHER_GAMES INT,
PUBLISHER_EMPLOYEES INT,
PRIMARY KEY(PUBLISHER_ID)
);
CREATE TABLE EMPLOYEE
(
EMPLOYEE_ID INT NOT NULL AUTO_INCREMENT,
EMPLOYEE_NAME VARCHAR(20) NOT NULL,
EMPLOYEE_ROLE VARCHAR(20) NOT NULL,
DEV_ID INT NOT NULL,
GAME_ID INT NOT NULL,
EMPLOYEE_NUM CHAR(10),
PRIMARY KEY(EMPLOYEE_ID)
);
CREATE TABLE GAMECREDITS
(
GAMECREDITS_ID INT NOT NULL AUTO_INCREMENT,
GAME_ID INT NOT NULL,
PUBLISHER_ID INT NOT NULL,
DEV_ID INT NOT NULL,
GAMECREDITS_YEAR INT,
PLATFORM_ID INT NOT NULL,
PRIMARY KEY(GAMECREDITS_ID)
);
CREATE TABLE PLATFORM
(
PLATFORM_ID INT NOT NULL AUTO_INCREMENT,
PLATFORM_PC BOOLEAN,
GAME_ID INT NOT NULL,
PLATFORM_PRICE NUMERIC,
PLATFORM_XBOOX BOOLEAN,
PLATFORM_SWOOTCH BOOLEAN,
PRIMARY KEY(PLATFORM_ID)
);
ALTER TABLE GAME
ADD FOREIGN KEY (PLATFORM_ID) REFERENCES PLATFORM(PLATFORM_ID),
ADD FOREIGN KEY (PUBLISHER_ID) REFERENCES PUBLISHER(PUBLISHER_ID),
ADD FOREIGN KEY (DEV_ID) REFERENCES DEVELOPER(DEV_ID);
ALTER TABLE PUBLISHER
ADD FOREIGN KEY (DEV_ID) REFERENCES DEVELOPER(DEV_ID);
ALTER TABLE EMPLOYEE
ADD FOREIGN KEY (DEV_ID) REFERENCES DEVELOPER(DEV_ID),
ADD FOREIGN KEY (GAME_ID) REFERENCES GAME(GAME_ID);
ALTER TABLE GAMECREDITS
ADD FOREIGN KEY (GAME_ID) REFERENCES GAME(GAME_ID),
ADD FOREIGN KEY (PUBLISHER_ID) REFERENCES PUBLISHER(PUBLISHER_ID),
ADD FOREIGN KEY (DEV_ID) REFERENCES DEVELOPER(DEV_ID),
ADD FOREIGN KEY (PLATFORM_ID) REFERENCES PLATFORM(PLATFORM_ID);
ALTER TABLE PLATFORM
ADD FOREIGN KEY (GAME_ID) REFERENCES GAME(GAME_ID);
INSERT INTO GAME (GAME_ID, GAME_NAME, GAME_GENRE)
VALUES
(001, 'GTA Sons Andres', 'Sand-Box'),
(002, 'Not Destiny', 'FPS'),
(003, "Red Alive Redemption", 'TPS'),
(004, 'Animal Passing', 'Simulation'),
(005, 'Knights Creed', 'Action'),
(006, 'Simpsins hit and run', 'Action');
INSERT INTO DEVELOPER
(DEV_ID, DEV_NAME, DEV_CITY, DEV_COUNTRY, DEV_CEO, DEV_GAMES)
VALUES
(010, 'Kawcho Games', 'Texas', 'usa', 'Joe Houston', 6),
(020, 'NotStar Games', 'Vancouver', 'canada' 'Sam Haser', 7),
(030, 'Boungie', 'New York', 'usa' 'Pete Larson', 3),
(040, 'Pinnaple Games', 'Halifax', 'canada', 'Sam Haser', 6),
(050, 'Noontendo', 'Toronto', 'canada', 'Bowser Doug', 10),
(060, 'Oobiesoft', 'Washington', 'usa', 'Larry Seinfield', 5);
INSERT INTO PUBLISHER
(PUBLISHER_ID, PUBLISHER_NAME, PUBLISHER_CEO, PUBLISHER_GAMES, PUBLISHER_EMPLOYEES)
VALUES
(111, 'Kawcho Publishing', 'Cassie Haley', 44, 20),
(222, 'Walmort Publishers', 134, 'Perry Plat', 45, 23),
(333, 'Kents Publishing', 156, 'Linda Frend', 23, 15),
(444, 'Coffee House', 145, 'Susy Paige', 45, 15),
(555, 'Off the ground publishing', 189, 'Kerry Doug', 60, 25),
(666, 'yourWay', 1, 'beff, jezos', 46, 25);
INSERT INTO EMPLOYEE
(EMPLOYEE_ID, EMPLOYEE_NAME, EMPLOYEE_ROLE)
VALUES
(100, 'Fiacre Julen', 'Ui design'),
(200, 'Sebastian Aneta', 'Animator'),
(300, 'Xavia Guy', 'Developer'),
(400, 'Oakley Jillie', 'Character Design'),
(500, 'Keaton Lula', 'Marketing'),
(600, 'Liv Randell', 'Developer');
INSERT INTO GAMECREDITS
(GAMECREDITS_ID, GAMECREDITS_YEAR)
VALUES
(101, 2012),
(102, 2020),
(103, 1999),
(104, 2015),
(105, 2017),
(106, 2019);
INSERT INTO PLATFORM
(PLATFORM_ID, PLATFORM_PC, PLATFORM_PRICE, PLATFORM_XBOOX, PLATFORM_SWOOTCH);
VALUES
(123, FALSE, 49.99, TRUE, FALSE),
(145, TRUE, 25.00, FALSE, FALSE),
(167, TRUE 26.99, FALSE, FALSE),
(189, FALSE, 12.49, FALSE, TRUE),
(134, FALSE, 69.99, FALSE, TRUE),
(156, FALSE, 36.00, TRUE, FALSE);
I appreciate any help I can get as this is relating to a final assignment of mine. The only solutions I've found through google and my teacher would take up like 60 update queries to fill in my tables.
Give me any advice you can :)