These games are played with cards laid out on the table that can be used either to attack or defend. In some versions of these games, a player may also have a hand of cards to use. These cards can be used by adding to the cards in the table or in some games used directly in combat.
In these games, turns usually are played by players adding cards from their hand to their cards on the table, then using the cards on the table to attack another player and discarding cards that were used up in battle. The next part of the turn is to replenish your hand by drawing from a face-down draw pile.
Cards are usually separated into these main categories. You have the fighting units, resources that can impact the strength of a fighting unit and action cards that have effects when played.
The objective is mostly the same, be the last player alive by killing off all other players, but this can vary. Sometimes the objective is to use all cards to successfully attack or to build a fighting unit to fit certain criteria.
Most of these games use specialized cards and fall into a category called Trading Card Games, but this is not always the case and many games can be found that use a standard card deck.