How do you make a game without any random elements?

1. Use conditionals instead: the world reacts to the actions taken by the player (or lack thereof) since the start of the game.
For example, depending upon the state of the world (such as changes caused by the player or game clock) and the time from the start of the game's clock, certain types of enemies will act in accordance with one set of rules when they are unaware of the player (or their actions), another ruleset when they are partially aware of the player (or their actions), and another when they are fully aware.

2. for some things that would otherwise operate on a basis of chance (such as a skill that has a 25% chance of dealing double damage when used), you can instead replace it with some criteria that would activate the event once met, for example the skill mentioned above may deal double damage every fourth time it has been used, or will deal double damage if used on a certain enemy, or in a certain location on the enemy, or when the enemy is in a certain state (less than half health, on fire, etc.)

3. Initial item placements and drops would be fixed, as would the initial placement of enemies, every map would always be the same, and both encounters and npc's may appear in certain areas based on the clock and game state, not by chance.

- the world would feel more real -

Basically the whole world of a game without randomness would be deterministic, but deterministic in the same way our world is, were every prior input from the past creates the state of the present, which in turn creates the output of the future, if you know everything about the universe in any previous state, you can use that data to predict every state it would take from that point on, but there is so many bits of data and there are so many different ways they interact with one another, that it may as well be random from, our perspective.

A world of rules, plain and simple, cause and effect, everything is an equation, an algorithm, simply one of such scale that we may never be able to solve it.