Symbols are important to us. Symbols communicate ideas in way language does not. Symbols have power, because our cultural upbringing gives them power. That is why people our countries use flags, and why in some parts of the world people burn those flags in protest. If you want to provoke an emotional response, use of symbols is an important tool.

One of the challenges of fictional settings is that ‘made-up’ symbols do not inherently carry the same emotional weight. Heretics ritually defiling the holy symbol of the Sun God Pelor (from the D&D Greyhawk setting) does not provoke the same response as seeing Templars defiling the Christian cross – at least most of the time. Players may see what is happening, cognate it, and decide upon their seeming character response, but it’s doesn’t really horrify at the same level.

One of the reasons for this is the symbol is not charged with meaning. The Sun disk of Pelor is little more than depiction of the sun. It’s not woven into any mythic cycle or wider belief system. This isn’t true of all made-up symbols – the Eye of Gruumsh (God of the orcs in the Greyhawk setting) refers to the Orc creation myth of how their all-father fought the God of Elves, lost an eye in combat and Orcs sprang into being from the blood he shed. I’d suggest the fact characters knowing this myth (in D&D it’s literal historical truth as well but that’s beside the point) is a good thing, that gives this symbol more emotional power. Consider a group of orcs carrying out an act of worship to their all-father, beneath the banner of the One Eye before entering battle against their hated elven enemies.

For larps set in some version of ‘the real world’ (including historical periods, and/or those with fantastical elements) may symbols are already charged with meaning. In fact, it can sometimes be hard to override the meanings embedded in the minds of the players.

Consider a boffer larp where the player characters are group of greek soldiers marching the army of Alexander during his invasion of India. Suppose they discover a native shrine, covering that simple Hindu good luck / sun symbol : the Swastika. To the Greeks who have never seen it before, this symbol carries little significance. To the players, some (particularly from some European countries) the level of emotional power would be great (indeed, doing this larp would actually be illegal in some European countries).

A challenge then when designing an experience in larp is finding a way to imbue symbols who emotive power, and how to change or override their existing meanings. My suggestions for how to go about this:

• Create a meaning behind the symbol. Give it a place in a mythic cycle or a message to carry. This doesn’t mean simply a literally meaning. The Christian cross doesn’t simply mean ‘Christianity,’ it represents the personal sacrifice of Jesus, with the empty cross denoting that he transcended death on the cross. This also allows for different types of interpretation; to the Templar who ritually defiles it, it represents the murder weapon used to slay their Lord.
• Spend effort communicating this meaning to players. When you are writing the cultural briefing material one of the most important points to get across is what symbols the culture confers meaning upon, and what that meaning is. In our culture black is the colour of mourning. In Viking culture, the lady of a house carries the keys to her food chest to signify her authority. The eagle of the god Jupiter carried by the legions of Imperial Rome has retained its power across history, and is still used on the American Presidential Seal today. If you are writing a culture (either a fictional one, or a historical one) you need to communicate this to players.
• Stating the meaning clearly in the briefing material is a good first step, but in itself probably not sufficient. In some major larps (e.g. Dragonbane, Totem) advance workshops are used to impart this meaning. In less grand projects, a larp can be designed to create experiences that build it up gradually. If you include a religious service in your plot/story that will begin to implant the meaning of the symbols into the minds of the players. With careful planning it’s possible to build up gradually, imparting a shadow of the meanings the characters would have gained from growing up in their home culture.
• Having lots of different cultures thrown together (as in common in fest larp) often does not allow time or space to really create and explore a culture in depth. Consider how many cultures your larp really needs. Having fewer cultures also gives you as an organizer more time to devote to each one, when it comes to designing and writing them. Cultural design is non-trivial; it took Professor Tolkien years, and he built upon existing mythic cycles. (e.g. the lidless eye of Sauron is inspired by the One Eye of Balor from Celtic myth, and goes one to inspire the aforementioned One Eye of Gruumsh)
• If you are using the classic PC/ NPC split, brief your NPCs to excessively react to symbols – this will demonstrate to players the correct reaction. If you believe in using such tools, you can create set pieces demonstrating this.