Another issue with the control system is how it deals with items that have been collected. Opening up a wallet, for instance, will reveal items inside, but while most adventures accept that you possess such items, Déjà Vu I & II don't. If you don't individually pick the items from the wallet so they end up in the main inventory, then the game doesn't acknowledge that you own them, meaning everything has to be scrutinized with a fine tooth comb. The same is true of doors — sometimes clicking on them will enable them to open, while other times you will have to click on "open" and then the door for the same effect. Little details like this combine to begin spoiling what is otherwise an entertaining game. However, considering that the game is crammed into such a small space with all this information on screen at any one time, the developers have done an admirable job of trying to fit everything in. Backgrounds are well drawn, if not exactly mind blowing, and are quite colourful in style. Music, on the other hand, is limited to about five irritating tunes throughout both games, and sound effects are only noticeable by their absence.

Puzzles are almost entirely inventory based or involve locating items containing important information in order to progress. While often logical, the puzzles lack variety, as this is pretty much all you do throughout both games, with the exception of a card game which you have to win in the second title. It's also something of a lonely experience — you never have any conversations and the handful of characters that are available are there either as a threat to your well being (in the form of clichéd gangsters and muggers) or serve a very small purpose such as driving you to your desired location, selling a newspaper, or serving out the cards in Black Jack. The latter is a very strange setup — in order to ensure a win, you have to give the dealer a specific newspaper clipping to gain his favour. If you don't, you have to be incredibly lucky (much like in real life gambling) and it is possible to run out of cash this way. Should you run out of money, the only viable option left is to wander around the desert (where death is lurking if you stay there for too long) looking for a $20 bill laying around, but as this is a random occurrence, it's possible to never come across it. Although avoidable when you know ahead of time, finding yourself stuck in such a predicament is ridiculously frustrating.

Similar to other early graphic adventures, it is possible to die in these games. Here it's through encounters with various muggers on the streets, along with several other events that can end your game prematurely. There are four encounters with muggers in total, three of which can be counterattacked with the fist icon (interestingly, using your gun results in instant death or arrest), while the latter can be avoided, or failing that, bribed with your cash. Most of the death opportunities are obvious, but should you find yourself pushing up the daisies, continuing the game restarts at the point just before your untimely demise, which cuts down the frustration factor significantly. The threat of death is more prominent in the second title, with the gangster world snapping at your heels; something that is tiresome when you just want to solve a puzzle. Some of the puzzles are also timed, and if not resolved, will result in being caught by one of the gangsters.

Most of the other ways to end the game are fairly self-explanatory: shooting people will lead to an automatic arrest, as will not paying the cab driver. However, others can be a case of trial and error. A nice touch is that however you accidentally end the game, a description of what happens next appears onscreen, which helps to develop the atmosphere. It's almost worth trying out all the possible outcomes to see what the game will tell you. Fortunately, both games can be saved at any point, which is a blessing for any portable adventure.

The redeeming positive among this sea of criticism is that both games are generally intriguing and keep you playing. The plotlines, while simple, are developed by well written text descriptions that give insight into the characters and do an ample job of adding atmosphere to the adventure. Moreso in the first game, clues are unraveled slowly and in a clever way, so at all times you only ever know as much as Ace Harding does, giving you a sense that you really are the Private Detective himself. The second game's storyline doesn't have the same pull as the first, but it still offers an entertaining play through. Overall, Déjà Vu I & II combined will take about eight hours to complete, which might not be the longest adventure on the GameBoy Color, but there's still plenty of gameplay to plough your way through.

While The Casebooks of Ace Harding suffer from a notoriously annoying interface and frustrating death occurrences, the storyline and written descriptions go a long way to make up for it. It's not the best handheld adventure by a long shot, but there's plenty of enjoyable gameplay here to discover if you can tolerate its many foibles.