Balancing the tone is another big challenge. Half - Life has a more action - oriented, science - fiction horror tone in a lot of ways. SCP can range from really creepy and disturbing to more light - hearted in some fan interpretations. Combining these two tones in a way that feels natural and engaging for the reader is no easy feat. Writers need to be careful not to make the story too dark or too goofy, but find that perfect middle ground.
Characterization can also be difficult. When you bring characters from Half - Life into the SCP universe or vice versa, you have to make sure their personalities are consistent. Gordon Freeman, for instance, has certain traits that fans expect. If he acts out of character in the crossover, it can be jarring for readers. Also, the SCP entities have their own 'personalities' in a sense, which need to be respected in the writing.