FailableDecodable.swift

struct FailableDecodable<Base: Decodable>: Decodable {
    var base: Base?

    init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        do {
            base = try container.decode(Base.self)
        } catch let error {
            print(error)
        }
    }
}

struct Game: Codable {
    let title: String
    let id: String
}

struct MyModel: Codable {
    let games: [Game]

    enum CodingKeys: String, CodingKey {
        case games
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        games = try container
            .decode([FailableDecodable<Game>].self, forKey: .games)
            .compactMap { $0.base }
    }
}

let json = """
{
    "games": [
                {
                    "title": "God of War",
                    "id": "GOT"
                },
                {
                    "title": "The Last of Us",
                    "id": "TLOS"
                },
                {
                    "title": "The Witcher 3",
                    "id": "TW3"
                },
                {
                    "title": null,
                    "id": null
                }
    ]
}
"""

let decoder = JSONDecoder()
let myModel = try decoder.decode(MyModel.self, from: json.data(using: .utf8)!)
print(myModel)