Tokyo Express is a highly detailed, comprehensive naval wargame about the 1942 naval battles around Guadalcanal that happens to have been designed for solitaire play.
I emphasize its detail and complexity because it is really a few steps above the norm for solitaire games and is really best suited for players very interested in naval warfare. The game has 88 pages of rules and 20 pages of charts. It's not for the faint-hearted.
The rules include provisions for all the sorts of things one would expect in a World War II tactical naval wargame such as primary and secondary guns, torpedoes, formations, illumination rounds, collisions. etc.
The heart of the game is an intertwined hex-by-hex movement and combat system that controls the Japanese side with procedures and die rolls that result in reasonable behavior. This all requires quite a bit of text to regulate.
The problem with solitaire games is that there's no one to share the work or help figure out the rules, making complex games burdensome for the player. Tokyo Express' rules help out by including many illustrated examples of play. Players should definitely play a the basic game a few times before jumping into the standard rules.
One reality of naval combat, especially the kind that occurred around Guadalcanal in 1942, that is hard to capture outside of umpired naval miniatures games is the fog of war. The player, as commander of a U.S. task force is faced with many of the same problems of his historical counterpart. Doctrinal and weapons limitations make the battles real challenges. Unlike many solitaire games, Tokyo Express is not a puzzle with a solution. Rather it's an exercise in managing chaos under conditions where you don't even know what you don't know.
The game components are typical Victory Games late 1980s standard. The map is paper but in full color. The counters are a mix of 1-inch long for ships and 1/2-inch markers. Gunnery combat results are determined using 120 cards, which provides a welcome break from all the die-rolling.
The charts are functional and well presented, but there are a lot of them. As mentioned, the rulebooks are also extensive, with a 24-page Basic Game and a 64-page Standard Game. These are very dense by current standards.
There are also two pads of ship rosters to track ship damage.
The game box rates the game from medium to very high complexity, but I think most players will find it tending toward the high end of the scale. Unlike many wargames, players are on their own learning this game and probably won't have someone able to teach them the rules. While there is a two-player option, I don't think it's used much. People interested in two-player games on the topic will probably use some other game.
Playing time is rated at 3-6 hours for the standard game. Again, battles will tend towards the longer end of that scale and the game will probably need to be left set up between playing sessions, which will require an undisturbed tabletop.
If you're interested in the topic Tokyo Express is a good acquisition. Long out of print, copies are often available on eBay. If you're just looking for a solitaire wargame, there are probably better choices such as Ambush!, B-17 or Raid on St. Nazaire which are considerably less complex.