R, now published as BraveRats, is another microgame by Senji Kanai of Love Letter fame. Similar to what happened with Love Letter, I found a lovely Star Wars themed version on BGG, and decided to make a copy. It is also a 16-cards game, but the gameplay is very different from Love Letter, and it is a 2-player-only game.
Both players start with all eight cards in hand. The two sets of cards are identical, and are numbered 0 to 7. Every round both players simultaneously play a card, and the higher number wins. Each card has some special text, which may change the result or affect subsequent rounds. Win four rounds, and you win the game. Naturally, the attraction of the game is all in these nifty powers. The #2 card forces your opponent to play a card first next round, so that you can decide what to play after seeing his card. The #6 card gives your next card a +2 bonus. The #1 card beats your opponent's #7 card and instantly wins you the game, without needing to count the number of rounds won. These powers and their interaction are what give the players something to chew on.
The game rules list 20 or so variants and alternative microgames, but I have not tried any of them.
I found these wonderful pictures for the card backs from Google.
The artwork for the Light side and the Dark side is different, but the powers are the same.
I have played R with non-gamers (my wife and children) and gamers (well, technically just "gamer" - Dith, no plural). For such a simple game, I am surprised that it is a variable depth game. You can play very casually, giving it minimal thought, little above rock-paper-scissors. You can also think about what your opponent may play, and what is the card in your hard with the highest probability of beating a card still in his hand, and how he may be considering that too and thus may decide to play the exact card to counter yours, and how you thus need to pick the card which counters what he will play, and how he may be thinking this far as well and may choose a different card which will counter the one you are picking. Of course, if you are sick of this thinking X steps ahead, you can randomly pick a card, but that would defeat the whole purpose of the game. You might as well play rock-paper-scissors.
I have played six games, but I don't feel I have mastered the various cards, knowing which ones are definitely suitable for the early game, and which ones for the late game, or mid game. Maybe it is impossible to pigeonhole the cards this way, which would be a mark of good design. I discovered that seemingly powerful cards can be vulnerable to quite a few other cards. It is rare to have a sure-win round (well, not counting the situation of you having played the #2 card in the previous round, thus forcing your opponent to play first this round).
Compared to Love Letter, R is a bit more thinky, because you have more cards to consider. In Love Letter, you only have two cards in hand and usually you can decide very quickly.
I am very impressed by the balance of the card powers in R. There is a counter for every card. There is no super card. There is no rubbish card. R is a great filler. It's the kind of game you can use to bet unpleasant tasks on, e.g. who is going to clean the toilet this week. I also think it works well when played in succession. From each game played, you get to glean how your opponent thinks, and that may help you in the next game. Maybe.