How many Half-Life games are there?
2
3
2
3
2
3
2
4
5
3
2
4
5
3
2
4
5
3
2
4
5
3
2
4
5
3
2
4
5
3
2
1
4
5
3
2
1
4
5
3
2
1
4
5
3
2
1
4
6
5
3
2
1
4
6
7
5
3
2
1
4
6
7
5
3
0
2
1
4
6
7
5
3
2
1
4
6
7
5
3
2
1
4
6
7
5
3
2
1
8
4
6
7
5
3
2
1
8
4
6
7
5
3
2
1
8
4
6
7
5
1
8
4
9
6
7
5
10
1
8
4
9
6
7
5
10
1
8
9
6
7
10
1
8
9
6
7
10
1
8
9
6
7
11
10
1
8
9
6
7
11
10
13
1
8
9
12
6
7
11
10
13
1
8
9
12
6
7
11
10
13
8
9
12
16
6
7
11
10
13
8
9
12
16
14
6
7
11
10
13
8
9
12
16
62
66
59
256
57
63
58