In letters rounds, 3, 4, or 5 letters will be shown. The object of the game is to find the shortest-possible word that uses all of the displayed letters. 10 points are awarded if you find the shortest possible word that uses them all, 9 points if your declared word is one longer than the shortest, 8 points if it is two letters longer, and so on. There are no minimum or maximum numbers of consonants or vowels you can pick. In rounds where there is no valid word that uses all the letters, the aim is instead to use as many of the letters as possible. So, in a 4-letter round, if there are no valid words that use all four, you need to try and find the shortest one that uses three. Working out when you should use less-than-all of the letters is a big part of the tactics in Omelette!
Numbers rounds work in a similar way to the regular numbers rounds, the important change here being that to score points you MUST use all six numbers in your solution.
Conundrums have one unique 9-letter solution as usual, but you won't be seeing 9 letters very often! As many letters as possible are removed, whilst making sure that the conundrum still has one unique answer. So you could be faced with having to find the 9-letter word from a scramble of anywhere between 3 and 9 letters (7 on average). For example, the scramble SEWSFNS has two letters missing, but it is still only possible to make one unique 9-letter word by adding two to these seven. In this case, the answer is SWIFTNESS.